The experiment was conduced to study the net energy (NE) requirement of Avian broilers aged from 1 to 21 days based on the measured NE of dietary corn and soybean meal. Two hundred and fifty one-day-old Avian broilers were randomly divided into 5 groups with 5 replicates of 10 broilers in each replicate, with the NE levels of the diets as 8.97, 9.25, 9.54, 9.83 and 10.11 MJ/kg, respectively, to investigate the effect of NE levels on the performance and nitrogen metabolism of Avian broilers aged from 1 to 21 days. The results showed as follows: the ADG and F/G in 9.83 MJ/kg NE group had extremely significant difference with 8.97 and 9.25 MJ/kg NE groups (P＜0.01), and had significant difference with 9.54 MJ/kg NE group (P<0.05), but had no difference with 10.11 MJ/kg NE group (P>0.05). The nitrogen availability in 9.83 MJ/kg NE group was significantly higher than that in other groups (P＜0.01). According to the regression analysis based on ADG and F/G, the NE requirement of Avian broilers aged from 1 to 21 days was 9.88 and 9.90 MJ/kg, respectively, and the average value was 9.89 MJ/kg. In conclusion, the net energy requirement of Avian broiler aged from 1 to 21 days is 9.89 MJ/kg.［Chinese Journal of Animal Nutrition，2011，23（1）：147-153］