This experiment was conducted to investigate the regularity of energy metabolism and deposition of 20 to 50 kg Chuanzang black pigs. In the experiment one, fifteen Chuanzang black pigs at the body weight of (20.17±3.46) kg were selected, 4 pigs were killed to measure carcass composition after 5 days adaptation period, others were randomly divided to 5 groups based on sex (4 replicates per group and 3 pigs per replicate), pigs in the same replicate were fed in the same pen, pigs in the 5 groups were fed the diets which digestible energy (DE) levels were 13.79, 13.37, 12.96, 12.54 and 12.12 MJ/kg, respectively, and the average daily feed intake (ADFI), average daily gain (ADG) and feed to gain (F/G) were measured. Experiment one was finished when the weight of pigs reached about 50 kg, then one pig chosen in each replicate was killed to measure carcass composition. In the experiment two, fifteen barrows at body weight of (48.34±4.07) kg come from experiment one were randomly divided to 5 groups (3 replicates per group and 1 pig per replicate), each pig was fed in a metabolic cage, pigs in the 5 groups were fed the diets as same as the experiment one, the metabolic experiment contained 3 days adaptation period and 4 days test period. The energy requirement model was built by the factorial method. The results showed as follows:dietary DE level affected the ADFI, ADG and F/G of 20 to 50 kg Chuanzang black pigs. The conversion efficiency of DE transformed metabolizable energy (ME) (ME/DE) was 97.26% to 98.10%, the mean value of deposition efficiency of ME (DED/ME) was 41.71%; the mean value of ME for maintenance requirement was 0.49 MJ/W^0.75 or 0.85 MJ/W^0.60 (DE for maintenance requirement was 0.50 MJ/W^0.75 or 0.87 MJ/W^0.60),the requirements of ME and DE of weight gain were 18.91 and 18.47 MJ/kg, respectively. It is concluded that the energy requirement model is set up as:DE(MJ/d)=0.504 W^0.75+18.91ΔW or DE(MJ/d)=0.867 W^0.60+18.91ΔW;ME(MJ/d)=0.492 W^0.75+18.47ΔW or ME(MJ/d)=0.847 W^0.60+18.47ΔW.