Abstract: In order to improve the drying quality of marine fish rich in polyunsaturated fatty acids,the experiment used Saury were raw materials to study the drying curve,sensory properties,color difference,metmyoglobin contents,acid value,peroxide value,thiobarbituric acid value,total volatile basic nitrogen value and fatty acid composition of semi-dried saury dried by hot air,air heat pump and nitrogen modified heat pump respectively. Comparative analysis showed that hot-air drying of semi-dried saury had high drying efficiency,but the drying quality was poor,fat oxidation was serious,and the sensory scores was the lowest. Air heat pump and nitrogen modified heat pump drying could improve the drying quality of semi-dried saury,and the semi-dried saury prepared by nitrogen modified heat pump had the lowest degree of fat oxidation,good color and the highest sensory score. The acid value of 10.01±0.20 mg/g,a peroxide value of 0.12±0.001 g/100 g,and a thiobarbituric acid value of 3.15±0.05 mg/kg,polyunsaturated fatty acids of 36.13%±%±4.31%,of which the retention of EPA and DHA was 24.78%±2.70%. The color difference was 11.66±0.52,the relative content of methemoglobin was 26.11%±0.64%. Nitrogen modified heat pump drying was suitable for the drying of marine fish rich in polyunsaturated fatty acids,and would be an ideal drying method for preparing high-quality semi-dried saury.