The work aims to determine the main nutrients in walnut kernels and to study the types and contents of fatty acids by selecting walnut kernels from 17 producing areas in Yunnan as the research object.The contents of total sugar, protein, crude fat and fatty acid were determined based on GB 5009.7—2016, GB 5009.5—2016, GB 5009.6—2016 and GB 5009.168—2016.The mass fractionof sugar, protein and crude fat in walnuts from 17 producing areas of Yunnan was 2.54%, 18.42%, and 66.44%. The fatty acids weremostly unsaturated fatty acids, mainly composed of oleic acid and linoleic acid. The content of fatty acid in Niangqing (Yangbi) was the highest with mass fraction of 92.23%. The content of fatty acid in Quren No.1 (Huizehuizhu) was the lowest, with mass fraction of 88.65%. The average ratio of polyunsaturated fatty acids n-6 series to n-3 series in walnut kernels was 8.49︰1, which wasbasically in line with the recommendations of the UN Food and Agriculture Organization ((5～10)︰1). The coefficient of variation of fatty acid α-linolenic acid was the highest, 29.41%, and the coefficient of variation of linoleic acid was the smallest, 9.89%. The ratio of PUFA/SAF of the large sand shell (JiangchuanXiongmei) was the highest, 14.89% and such walnut kernel was the best to lower blood fat and evaluate fatty acid properties.According to the analysis of different varieties of walnuts in Yunnan, Yunnan walnut kernels are rich in nutrients and beneficial to varieties, and have the value of in-depth development, processing and utilization.