Abstract: The early pregnancy diagnose was experienced by 3% and 5% CuSO4 respectively in 57 cows, then checked up their accuracy through rectum-check. The result showed that the total accuracy rate of used by 3% CuSO4 was 87.14%, the group used by 5% CuSO4 was 84.80%. But the accuracy rate in the tow groups was best with milk sample check in 31~50 days after breeding, the average value was 90.35%; the negative accuracy rate by 5%fell comparing to 3%, the none-pregnancy rate was increased because diagnose by mistake. It is indicated that the early pregnancy diagnose was done better with 3% CuSO4 and the method was feasible, the milk sample of 31~50 days after breeding at noon was best to be diagnose the cow early pregnancy in practice.