Abstract: Miichthys miiuy Basilewsky is a commercially important marine fish in China. To understand the relationship between body mass and morphometric traits of M. miiuy, body mass (Y, g) and other eight morphometric traits (cm), e.g., total length (X₁), body length (X₂), head length (X₃), trunk length (X₄), tail length (X₅), tail handle length (X₆), tail handle height (X₇), and body height (X₈) of 524 individuals of about 12-month-old M. miiuy were measured in this study. The methods of correlation analysis, multiple regression analysis, and path ana-lysis were used to analyze the data. Also, the best model reflecting the relationship between morphometric traits and body mass were obtained through model fitting screening. The results showed that the correlation coefficients between every two traits ranged from 0.834 to 0.941, and all reached significance level (P<0.01). And body length was ruled out from the multiple regression analysis by the method of multicollinearity diagnosis. We established a regression equation using the rest morphologi-cal traits as variables and body mass as dependent variable, in which direct and indirect path coefficients and determinant coefficients were calculated. Four morphometric traits achieved highly significant levels (P<0.01), and they were the main decisive morphometric traits linked to body mass. The multiple linear regression model equation was established as Y＝-444.188 +7.943X₁+12.861X₄ +38.254X₇ + 42.722X₈. Among them, the trait with the strongest direct effect on body mass was the body height (0.351), then the total length (0.335). In addition, the best model fitted for the individuals was y=0.013 x^2.891 for total length, y=2.028 x^2.751 for body height. The method of model fit test showed the accuracy of total length estimated body mass was higher than that of body height. This research may provide an important reference for the effective use of morphological traits for breeding of M. miiuy.