Abstract: The objective of this study was to analyze the distribution of the somatic cell counts （SCC）and its correlation with lactation month and milk composition based on records of Dairy Herd Improvement （DHI）from 2012 to 2013 of a dairy farm in Heilongjiang province. The results showed that the total average SCC in raw milk was 140 000/mL,the ration of the dairy cows with SCC below 200 000/mL was 56.70 %. SCC was higher in June and August, and the positive rate of mastitis reached the highest value of 27.25% in October. It would produce loss when the SCC was higher than 150 000/mL in this dairy farm, and the economic losses caused by the cattle with SCC higher than 500 000/mL accounting for 71.45% of the total economic losses. SCC was negatively correlated with milk yield and was positively associated with milk protein. The results obtained in this study will provide scientific evidences for the better using of DHI evaluation system to regulate feeding management and prevent mastitis.