Abstract: The genetic diversity and relationship among 10 populations of mulberry wild silkworm,Bombyx mandarina,from 7 regions of China and two races of silkworm,Bombyx mori,were analyzed by AFLP technique.The results showed that the genetic distance of inter- and intra-populations in mulberry wild silkworm from three regions,Hangzhou,Shaanxi and Chongqing,was even larger than that of races in domestic silkworm.Extensive genetic variation existed among 10 populations of mulberry wild silkworm.The genetic distance between these populations ranges from 0.164 to 0.444 (the average value is 0.3826) and the average heterozygosity value of them is 0.061,which also indicates that mulberry wild silkworm is rich in genetic diversity.