Abstract: To estimate genetic variation and provide genetic information for resource protection and breeding efforts, individuals of the invasive red swamp crayfish (Procambarus clarkii) from four populations along the lower reaches of the Yangtze River (Nanjing, Xuyi, Hefei and Nanchang) were characterized using 17 mi-crosatellite loci. In these populations, the mean observed heterozygosity (Ho), mean expected heterozygosity (He), and mean polymorphism information content (PIC) ranged from 0.4322 to 0.4826, from 0.4024 to 0.6121, and from 0.3408 to 0.5624, respectively, indicating a medium level of genetic diversity. The highest and lowest genetic diversity were found in the Nanjing population and Hefei population, respectively. Gene flow (Nm) ranged from 1.3729 to 5.9161, and population differentiation (Fst) ranged from 0.0405 to 0.1540. Cluster analysis using the UPGMA method showed that the Nanjing and Nanchang populations clustered first, and then clustered with the Xuyi population, and finally all groups together clustered with the Hefei population.