This study aimed to investigate the relationship between morphological traits and body weight and fillet yield in largemouth bass, with the goal of selecting individuals with a high weight gain rate and fillet yield. Largemouth bass widely used for breeding in China (Northern subspecies, YouLu1, YouLu3, and China-Taiwan) were selected for the experiment. Body weight (Y), fillet yield (Y_F), total length (X1), body length (X2), body height (X3), body thickness (X4), head length (X5), interocular distance (X6), eye diameter (X7), snout length (X8), caudal stalk length (X9), and caudal stalk height (X10) were measured. Correlation analysis, path analysis, coefficient of determination analysis, and multiple linear regression analysis were conducted to identify the morphological traits affecting body weight and fillet yield. The results show that total length (X1) and body height (X3) have the greatest influence on body weight, while caudal stalk height (X10), caudal stalk length (X9), body length/caudal stalk length (X2/X9), and body weight (Y) have the greatest influence on fillet yield. Multiple regression equations were constructed for each subspecies. and their influence on body weight and fillet yield were determined for four largemouth bass subspecies: Northern subspecies, YouLu1, YouLu3, and China-Taiwan. For the Northern subspecies, the regression equation for body weight was Y=–622.778+21.21X1+45.305X3+16.633 X8+17.431X10, and for fillet yield, it was Y_F=12.394+3.683X10+24.152X1/X2. The regression equation for YouLu1 was Y=–453.528+54.855X3+5.913X1+22.708X5+41.194X7 for body weight, and Y_F=69.985+3.144 X9–0.020 Y–24.844X1/X2 for fillet yield. The regression equation for YouLu3 was Y=–531.600+56.933 X3+12.502X1+28.466X8 for body weight, and Y_F=120.795–3.221X2/X9–41.856X1/X2–2.495X3/X10 for fillet yield. Finally, for China-Taiwan, the regression equation for body weight was Y=–660.952+20.889 X1+60.774 X3–10.605X5+21.372X4, and for fillet yield, it was Y_F=43.928+0.011Y+0.452X9. These equations enable the selection of largemouth bass with a high weight gain rate and fillet yield. In addition, the study suggests that largemouth bass with a slender body type index (2.60