Abstract: [Objective] To study the changes of free fatty acid content in raw milk at different processing stages from raw milk to finished milk. [Method] The data of fat,protein and free fatty acid content of 600 raw milk and finished milk of a brand company were grouped according to the season and production and processing stage（raw milk to finished milk）,and the one-way ANOVA was performed. [Result] The season had a significant difference on the content of free fatty acids （FFA） in milk（P<0.05）,and the content of free fatty acid in spring raw milk was significantly higher than that in autumn raw milk. The average content of free fatty acid at different production and processing stages changed significantly,from raw milk to finished milk,the raw milk was the lowest,followed by 19 canned milk（pasteurization process）,and finished milk was the highest. While the free fatty acid content of raw milk and finished milk changed significantly,the fat content changed slightly and the difference was not significant（P<0.05）.The difference in protein content between the raw milk collected in spring and finished milk,but the difference was significant between the raw milk collected in spring and the raw milk collected in autumn（P<0.05）. [Conclusion] The free fatty acids (FFA) in milk undergo changes during different processing stages from raw milk to finished milk. Therefore, it is suggested to further determine the types and threshold range of FFA in milk to achieve fine-tuned management of its content, thereby driving the dairy industry towards higher quality and healthier development.

Key words: milk, season, different production and processing stage, free fatty acid