To screen effective breeding strategies for Procambarus clarkii and address the shortage of high-quality seedlings，this study compared the reproductive performance of germplasm populations formed through self-rearing，external introduction，and selective breeding.Additionally，and using regression analysis and structural equation modeling （SEM） were employed to elucidate the key phenotypic traits and their pathways influencing reproductive performance.The results showed that P. clarkii from the selectively bred population exhibited significantly higher absolute fecundity ［（621.35±173.43） eggs/female］，relative fecundity ［（15.53±2.57） eggs/g］，total egg mass ［（4.31±1.53） g］，and egg-carrying rate （94.7%） compared to individuals from the introduced population ［（374.35±85.75） eggs/female，（13.15±2.42） eggs/g，（3.36±0.82） g，71.7%； P<0.05］ and the self-reared population ［（190.54±79.08） eggs/female，（12.30±3.11） eggs/g，（1.44±0.67） g，52%； P<0.01］.The absolute fecundity of the introduced population was significantly higher than that of the self-reared population （P<0.05），but there was no significant difference in their relative fecundity.SEM analysis revealed that the standardized path coefficient from carapace width to absolute fecundity （0.542） was higher than those from body weight （0.451） and total egg mass （0.387），indicating that carapace width is the most critical phenotypic trait influencing absolute fecundity.Carapace width indirectly enhanced absolute fecundity by influencing both body weight and total egg mass，with the model showing a good fit （CFI=0.918，GFI=0.917，RMSEA=0.056）.Furthermore，the carapace width of the selectively bred population ［（2.52±0.19） cm］ was significantly greater than that of the introduced population ［（2.39±0.13） cm，P<0.001］ and the self-reared population ［（1.91±0.31） cm，P<0.001］.These results indicate that selective breeding is an effective strategy for enhancing the reproductive performance of P. clarkii，with carapace width being the key phenotypic trait responsible for this improvement.