Online bookings at large selections of hostels can be found at www.hostelbeijing.com.
Here are some buget hostels listed on wikitravel.com with more detailed information:
Red Lantern House, No.5 Zhengjue Hutong, Xinjie Kou, Xicheng District, +8610 66115771/66169477 (firstname.lastname@example.org). Absolutely adorable hostel with a genuine Chinese feeling. The courtyard in the middle is a great place to hang out, talk to new friends or just sit by yourself and read. Its location in a classical Hutong adds to the feel of experiencing the real China. They offer airport pickup for 160 yuan Dorm beds from 45 yuan, singles from 130 yuan, doubles from 140 yuan.
Beijing Join Inn, No. 14 Qinmao Hutong, Zhaodengyu rd, Xicheng District. Tel. 86-10-66135481, 13552794897. Contact Johnny. This place is located within the popular Xinjiekou district close to the city centre. Located in one of Beijing's hutongs, the hostel is close to key bus and subway services, making sightseeing relatively simple. From Jishuitan subway station, Take the C exit and turn left, walk about 500 meters along the XIN JIE KOU BEI street until you reach a McDonalds restaurant, intersecting with XI ZHI MEN NEI street. Walk along XI ZHI MEN street to the first set of traffic lights (about 120m). Turn left here to walk along ZHAO DENG YU LU. You should be able to see the hostel's sign in the third alleyway (QINMAO Hutong) on your left. The hostel appears to give the best value for money with 30 yuan for a dormitory bed, 180 yuan for a triple room and 160 yuan for a double room (the price depends on the season). The place has a great family/chilled out vibe.
Qiao Yuan Fandian. Located not far west from Beijing South train station. About 20 yuan from Beijing Zhan (Beijing Train station) by taxi, or take buses 744 or 20; best from Qianmen near Tiananmen Square. There's a whopping 200 yuan deposit but 4 bed dorms with a/c are reasonably priced at 31 yuan or 260/360 yuan for standard suites, the more expensive option in the building in the back (newer). Level 6 has a laundry, kitchen, and travel agency. Internet access is located towards the train station (look for the fish net character (网) on the signs, or ask for 'wang ba') or a few blocks away to the west near KFC, McDonalds and a supermarket. Plenty of eating is nearby, and also don't miss the Art Deco interior of a hotel/restaurant when its lit up at night (head towards KFC).
Beijing City Central Youth Hostel, Located directly across from Beijing Zhan (Beijing train station). Dorms 60 yuan (4-8 beds). Doubles with shared bathrooms 160 yuan.
Beijing Saga International Youth Hostel, No. 9 Shijia Hutong, Dongcheng District. Tel. 86-10-65272773, 65249098. This place is about a 15 minute walk from the Beijing Main Railway Station. From the station, follow the road North past the Beijing International Hotel. After about a ten minute walk look for the hostel sign with an arrow pointing down one of the hutongs on the left side. The hostel is very popular with backpackers. They charge 180 yuan for a triple room, 160 yuan for a double room and 40-50 yuan for a bed in a dormitory (the price depends on how many beds are in the room). There's a restaurant on the top floor. The staff speaks some English.
New Dragon Youth Hostel, just along from Saga (above) in Shijia Hutong, Dongcheng District, sometimes used for their overflow. Fairly dirty and unpleasant inside despite the nice facade. The dorm rooms are in the basement and the place has almost none of the facilities it advertises. Best to avoid.
Beijing Far East Youth Hostel, 90 Tie Shu Xie Jie, Xuan Wu District. Tel. 86-10-51958811. It's in a traditional Chinese courtyard, about 10 minutes walking from Tiananmen Square. The Far East Youth Hostel has become very famous after having been added to major travel guides. During summer time you should book one week in advance.
Leo's Hostel, Tel: (10) 63031595 or (10) 63033318. A good alternative to the Far East and is just around the corner. Leo's Hostel is in the same road as the Far East, has a free Playstation 2, Internet, Pool, lockers, maps, guides, magazines etc. It is well known for its friendly staff and lively bar atmosphere. It has a beautiful courtyard, with dorm rooms (45-70 yuan) as well as private rooms (160-200 yuan).
Changgong Hotel, Tel: (10) 63015088 or (10) 63032665. One of the cheapest places in the Qianmen Hutong. It has a traditional architecture and is just next door from Far East and Leo's. Don't try to find any of the narrow roads on the map. Navigation is only possible by asking or in a rickshaw. Dormbeds are 35 yuan, a triple room is 210 yuan.
Eastern Morning Youth Hostel, Tel: (10) 65284347. A great budget option if price is your primary concern. The hostel is located in the basement of the Oriental Plaza shopping/office/residential complex next to Wangfujing. Private rooms cost about 90 yuan per night - book in advance. The staff does not speak much English but are friendly. Internet access is available at 10 yuan per hour. The hostel is located on Dongdan Santiao (which runs behind Oriental Plaza). It is a 5 minute walk to the Dongdan or Wangfujing subway stations and about a 15 minute walk to the International Hotel airport shuttle stop.
Jing Yi Shi Hotel, located between Leo hostel and Far East Y/H, Tel: 86-10-63043822. The hotel is traditional siheyuan and has beautiful courtyard. The staff does not speak much English but are very friendly. There are two PCs available, Internet access costs 10 yuan per hour. Twin room costs 150, 180, 220 yuan.
Houhai Youth Hostel, Tel: 0086-10-66128458, mobile: 0086-13439801676. One of the most mysterious and charming old-Beijing style courtyard inns, which is located in Sanbulao Hutong in Houhai. Its only 5 minutes by foot to the Houhai Lake. They provide free services such as a map of Beijing, tour of HuTong (traditional courtyard house), tea, Internet access, satellite TV & DVD access, usage of kitchen, baggage deposit. The staff speak English, and there is parking as well. Each single rooms cost $15 and up. Dorm beds cost $6 and up.