Rainbow trout are cultured widely throughout the world for supplementation in natural ecosystems and for commercial aquaculture. In 1959 it was firstly introduced to China from Korea. After introduction from America and other countries such as Norway, Denmark, and so on, rainbow trout were now cultured in about 20 provinces in China. In this study, microsatellite DNA was employed to assess the genetic variations between 6 cultured populations of rainbow trout (American golden trout, American Donaldsons, Norway, Denmark, Finland, and Bohaizhan). The results showed that in these 6 cultured populations the average number of allele (A) was 2.89 to 4.22; average number of effective allele (Ne) was 2.15 to 2.78; the value of average observed heterozygosity (Ho) in six populations was 0.4802 to 0.6786; the value of average excepted heterozygosity (He) was 0.5052 to 0.6211; and the value of average polymorphism information content (PIC) was 0.4298 to 0.5762. Hardy-Weinberg equilibrium analysis revealed that all of these 6 populations showed a remarkable genetic disequilibrium at loci AY039634, AY039638, AY0396466. Only at locus AF375034 all of 6 populations showed equilibrium. The genetic distance of six cultured populations was calculated and cluster analysis was also carried out.