Abstract: This study adopted freezing unfreezing method to extract the crude fatty oil from the livers of skate and response surface methodology to optimize the deacidification during refining process and then analyzed the physical and chemical properties, fatty acid composition and content changes of skate liver oil. The result shows that the optimal process conditions were as follows: degumming agent with 5% oil weight, deacidification by heating 20% sodium hydroxide of oil weight at 75 ℃ for 20 min, decolorizing with 8% activated clay of oil weight and deodorization by vacuum distillation for 60 min at 40 ℃, 60 r/min. The color and physical and chemical properties of the refined skate liver oil obtained under these conditions were in line with the level I of national standard Fish oil. Its fatty acid composition has no obvious difference from that of crude skate liver oil, cod liver oil or shark liver oil, which contain 23 kinds of C14~C22 fatty acids. However, there were some differences in contents. The EPA content of refined skate liver oil was 8.65%. It was lower than 10.17% of crude skate liver oil but much higher than 2.74% of shark liver oil and approximately equal to 8.78% of cod liver oil. However, the DHA content of refined skate liver oil was the highest at 15.04%.