The volatile flavor compounds in donkey, pig, cattle and sheep leg meat were qualitatively and quantitatively detected by gas electronic nose and gas chromatography-mass spectrometry, and the fatty acid composition was also determined by gas chromatography analyzer. The results of gas-phase electronic nose showed that the flavor difference between the leg meat from donkey and pig was not obvious. However, the significant difference between that from donkey and beef was observed, with 76 volatile substances detected by GC-MS, mainly aldehydes. Aldehydes accounted for 70.71%, 75.36%, 48.76%, 55.94% in donkey, pig, beef and sheep, respectively. The content of n-hexanal with faint scent and grass smell was the highest, accounting for 29.89%, 20.46%, 12.74% and 10.78% of the total flavor respectively. The total content of main saturated fatty acids in donkey, pig, beef, and sheep was 30.01%, 39.05%, 36.34%, and 48.42%, and unsaturated fatty acids were 63.19%, 57.10%, 49.03%, and 43.71%, respectively. In conclusion, the main compound affecting the flavor characteristics of donkey meat was n-hexanal, which originated from the oxidative decomposition of linoleic acid.