The trial was conducted to study the relationships between milk energy (E, MJ/kg) and the contents of milk protein (P), fat (F), total solid content (TSC) and lactose (L) in water buffalo. The trial improved the milk energy determination method by using freeze-drying method to get milk powder instead of oven-drying method, and the raw milk samples were collected from the second week to the eleventh week of lactation. Two hundred and forty samples were collected for each parameter, and the final number of samples with complete information was 233. The results showed that the contents of milk protein, fat, total solid content and lactase, and milk energy were (4.7±0.2)%, (6.8±0.5)%, (17.0±0.5)%, (5.5±0.2)% and (4.4±0.2) MJ/kg, respectively. The relationships between milk energy (E, MJ/kg) and milk composition were calculated by the function of LINEST in Excel 2003. It was found that the milk energy could be estimated using the following equations: E=0.318 1F+0.333 5P+0.085 5L+0.421 6 (n=233, R2=0.828 142, P<0.000 1), E=0.325 7F+0.326 7P+0.870 9 (n=233, R2=0.820 045 86, P<0.000 1), E=0.346 781TSC+0.011 291F－1.446 069 （n=233, R2=0.826 169, P<0.000 1） and E=0.352 496TSC－1.488 11 （n=233, R2=0.825 623, P<0.000 1）. In conclusion, high correlation existed between water buffalo milk energy and the contents of milk protein, fat, lactose and total solid content, therefore, these equations could be used to estimate water buffalo milk energy.［Chinese Journal of Animal Nutrition, 2010，22（4）:964-968］