Abstract: The optimal extraction conditions and their effect on oil quality and fatty acid composition of fish oil extracted from the liver and fat (1:1) of Ctenopharyngodon idellus by using diluted alkaline hydrolysis method was investigated. The results indicated that the extraction ratio, iodic value, acid value, peroxide value and soap stock content were significantly affected by extraction conditions. The optimal extraction conditions determined by extraction ratio, iodic value, acid value, peroxide value and saponified matter content were that the volume ratio of the minced liver and fat of Ctenopharyngodon idellus and water was 1∶1, the immersion time in water bath at 45℃ was 5min, the pH of the sample solution was adjusted to 10.0 with NaOH solution (1∶1, W/V) , and the sample solution was precipitated in 10mL 4% NaCl solution for 5min at 60℃, then the fish oil was obtained after centrifugation. The yield of fish oil extracted from Ctenopharyngodon idellus by the optimal extraction conditions was 84.81%±0.56%. The results of the analysis of the prepared fish oil showed that it comprised of 22 kinds of fatty acid, i. e. 16∶0, 18∶1n-9, 20∶5n-3 (DHA) and 22∶6n-3 (EPA) , and saturated fatty acids accounted for about 30%, which stearic acid was maximum for 18.5%, unsaturated fatty acids accounted for about 60%, which oleic acid was maximum for 18.6%, and EPA accounted for 0.7%, DHA accounted for 0.5%.