Abstract: In order to understand the characteristics of cow milk in southern mountain pastures,improve the quality of raw milk in mountain pastures,and provide a theoretical basis for rational development and utilization,this article compared and analyzed the physical and chemical indicators(conventional ingredients,mineral elements,amino acid composition,volatile components)and microbial diversity of fresh milk in Nanshan Ranch and Suburb Ranch in Hunan. The results showed that:Nanshan Ranch cow milk and Chengjiao pasture cow milk had significant differences in their conventional nutrients. Among them,the milk in Nanshan Ranch content of free fatty acids was as high as 5.34 mg/kg,and the contents of iron and zinc were 5.200 and 6.390 mg/L,which were significantly higher than Milk in the suburban pastures;the total amino acid content in the milk in Nanshan pastures was 3.102 g/100 g,which was lower than that in the milks in the suburban pastures;a total of 13 volatile substances were detected in the milk in the suburban pastures,and a total of 11 substances were detected in the determination of volatile components in the milk in the Nanshan pastures Lower than cow milk in suburban pastures. The determination of microbial diversity found that the composition ratio of the bacterial groups between the two pastures was significantly different. The bacterial samples of the two suburban pastures were rich in diversity and the composition was roughly the same,the dominant abundance was Enterococcus,and Acinetobacter in the milk of Nanshan pasture for the dominant flora. Comprehensive analysis showed that the milk of the same breed was greatly affected by geographical environmental factors,and the conventional ingredients,minerals and amino acid content of milk in different pastures were significantly different;the microbial diversity was significantly affected by environmental factors.