This paper investigated the relationship between tyrosin composition and irradiation sterilized dried fish.The tyrosin composition was determined by high performance liquid chromatogram-fluorescence detector.The method of sample preparation was also developed,including extraction,separation and concentration.The ratio of p-tyr and o-tyr was used to identify whether sample was irradiated.The detection limit was 16.6～21.0 ng/mL.The linear range was from 16 ng/mL to 3 800 ng/mL,and linear correlation was good(R2 = 0.999 7～0.999 9).Recovery of o-tyrosine and p-tyrosine were 82.7% ～98.3% and 83.3 %～93.8%,respectively.The relative standard deviation was less than 7.8%.