Abstract: In order to define the correlation between milk protein content and other indicators of DHI and the relationship between milk protein levels and months in Chinese Holstein dairy cows under different milk protein levels, the DHI data of 600 Chinese Holstein dairy cows from a pasture in Heilongjiang Province were was measured, then were divided into low level group（milk protein content≤3.3%）, normal group（milk protein content＞3.3%～≤3.7%） and high level group（milk protein content＞3.7%） taking the DHI data as base. The correlation analysis of inter-group, intra-group, individual data and external temperature（in different months） was carried out by SPSS 22.0 and Sankey diagram. The results showed that there were extremely significant differences in milk protein content, milk yield, milk fat rate, lactose rate and urea nitrogen index among Chinese Holstein dairy cows with different milk protein levels（P＜0.01）. The content of milk protein of three groups was extremely significantly negatively correlated with milk yield and lactose rate（P＜0.01）, and extremely positively correlated with milk fat rate（P＜0.01）. Milk yield was extremely negatively correlated with milk fat rate（P＜0.01） and extremely positively correlated with lactose rate（P＜0.01）. There was a extremely significant negative correlation between the lactose rate and the lactose rate（P＜0.01）, and a extremely significant positive correlation between the lactose rate and the urea nitrogen（P＜0.01）. Lactose rate was significiantly or extremely significiantly positively correlated with urea nitrogen（P＜0.05 or P＜0.01） and extremely negatively correlated with somatic cell number（P＜0.01）. The proportion of dairy cows with high milk protein level was relativelyhigher in the cold months（November 2018—February 2019）, accounting for 75.69%-89.24%; but relatively lower in the warm months（July 2018—September 2018）, accounting for 49.62%-62.26%. The results indicated that the milk protein content was extremely significantly correlated with milk yield, lactose rate and milk fat rate, and the temperature has a significant influence on the milk protein content of Chinese Holstein dairy cows.