This experiment was conducted to study the effects of high energy feed on physiologic indices and production performance of cows under heat stress and its mechanism. Thirty three lactating Holstein cows was used in the experiment and divided into three groups randomly with 11 cows in each group. The cows in control group were fed basal diets, those in treatmentⅠwas supplemented with roast soybean, and those in treatmentⅡwas supplemented with rapeseed. The results showed that the high energy feed had no effect on the dry matter intake of cows. The milk yield of treatmentⅠhad significant (P<0.05) increase by 3.27% compared with that of control group. Milk yield of treatment ⅠandⅡboth increased by 2.28% and 7.31%, respectively compared with that before experiment, however, the control group had slight delclining. The high energy feed had no effect on the milk composition basically. The rectal temperature of different treatments was similar, the breath frequency of treatment Ⅰwas significantly (P<0.05) increased compared with that of the control group, and the two treatments had significant higher heartbeat times (P<0.05) compared with control group. It was concluded that the two kinds of high energy feed could increase milk yield and relieve the heat stress of the cows in a certain degree.