Abstract: The objective of the experiment was to study the transition of digestible model, energy conversion rate and the characteristics of energy metabolism of the calves. Three 2-day-old Holstein male calves were selected to carry out digestion-metabolism experiment. The results showed that the digestibility of the diet energy declined gradually with the month, the average was 73.73%, the metabolic rate of digestible energy stabilized during the first 3 months and then decreased from 3rd to 5th month, finally returned to normal, the average was 84.68%, the metabolic rate of gross energy declined gradually during the first 5 months and then returned, the average was 62.68%, the ratio of urinary energy to digestible energy was 11.44%,the ratio of methane energy to digestible energy increased during the first 4 months and then decreased during the last 2 months, the average was 3.65%, the ratio of heat production to digestible energy showed a trend of increased firstly and then decreased, the average was 43.86%, the ratio of retention energy to digestible energy was 41.01%. The average heat production was 395.71 kJ/kg W^0.75, the net energy for gain was 10.97 MJ/kg. The results indicate that the fasting heat production of calves was more than that of mature cows, while the net energy for gain was less than that of mature cows.