Abstract: The distribution and depletion rules of MG and its metabolite LMG in organizations of perch were investigated,that were dipped in the concentration of 0.15 mg / m L MG for 1 h,and that reared in tanks containing( 0) indoor.Skin,back muscle and liver of perch were analyzed by ultra- performance liquid chromatography- tandem mass spectrometry carrying out qualitative and quantitative analysis of target analytes.The concentration of LMG was much higher than that of MG during the experiment.The concentration of MG and LMG in liver was highest.The result of MG concentrations in back muscle,skin,liver of perch showed that the order of 3 kinds of tissues concentration levels of MG from high to low were respectively liver( 94.86 ±8.12) μg / kg,skin( 19.35 ± 1.88) μg / kg,back muscle( 7.47 ± 0.45) μg / kg.MG was not detected in back muscle,skin,liver of perch at 168 h,960 h,2160 h. The order of 3 kinds of tissues half- time of MG from long to short were respectively liver( 7.22 d),skin( 7.22 d),back muscle( 1.44 d).The order of 3 kinds of tissues concentration levels of LMG from high to low were respectively liver( 3607.13 ± 189.56) μg / kg,back muscle( 103.65 ± 14.97) μg / kg,skin( 82.10 ± 7.64) μg / kg. The order of 3kinds of tissues half-time of LMG from short to long were respectively liver( 14.44 d),skin( 28.88 d),back muscle( 28.88 d).Even after 2544 h of elimination,LMG in back muscle,skin,liver even could be detected.