In this study, an open-circuit calorimeter for poultry was used to carry out an energy metabolism experiment to investigate the net energy conversion efficiency of different layer breeds under the same feeding environment and the same diets. Every 60 Hy-Line Brown and Jilin-Luhua chickens at laying peak were selected and fed an identical corn-soybean meal diet in the same henhouse with a 2×2 factorial design. Formal experiment period was 58 days after 7-day advanced experiment period. Every 9 birds from each group were selected respectively on the day 20 and day 40 of the formal experiment period, and after being weighed, they were randomly placed into 6 individual respiration chambers with 3 birds per chamber (a kind of bird was tested by three chambers, and continuous measurement for twice) to measure the value via gaseous exchange and total excreta collection for 9 days, including 3 days of dietary adaptation period, 3 days of respiratory calorimetry and 3 days of fasting heat production; meanwhile the digestion metabolism test was simultaneous with the respiratory calorimetry. The results showed that the laying rate and average egg weight of Jilin-Luhua chickens were significantly lower than those of Hy-Line Brown chickens (P<0.05) in the case of body weight and feed intake difference between them was not significant (P>0.05). The apparent metabolizable energy, heat production of feeding and fasting heat production of Jilin-Luhua chickens were significantly higher than those of Hy-Line Brown chickens (P<0.05), which made the retained energy and apparent metabolic energy conversion to net energy efficiency (apparent metabolic energy to net energy ratio) were significantly decreased (P<0.05). Apparent metabolic energy to net energy ratios were as follows:Hy-Line Brown chickens were 72.21% and 71.13%, and Jilin-Luhua chickens were 68.54% and 66.31%, respectively. In conclusion, as more heat production, the net energy conversion efficiency of Jilin Luhua chickens is significantly lower than Hy-Line Brown chickens at the same diets and environmental conditions.