Abstract: The silkworm is an important economical insect in sericultural field. Its major production-economic characteristics are polygenic. In this study, three F2 populations (second generation) derived from three cross between three pairs, parents of Lemon Khorasan (as maternal) and 107 (as paternal) lines. we contacted AFLP (amplified fragment length polymorphism) technique for mapping genetic factors or QTLs that effect on Cocoon Shell Weight (CSW) trait. Following it we used 20 selected primer combinations of PstI/TaqI and DNAs were individually extracted to phenol-chloroform method. They digested by two restriction enzymes (TaqI and PstI) and also produced DNA fragments amplified by appropriate adaptors separately. After transferring of DNAs samples on annealed 6% polyacrylamide gels and genotyping of individuals, the linkage maps of each population were drawed. The QTLs for cocoon shell weight trait in LRS = LRT>12.5 (LOD>2.71) threshold level based on permutation test (n = 1000) and using compound interval mapping methods were analyzed and detected 5, 1 and 1 QTLs that were localized on linkage groups 9, 11; 12 and 24 in each studied F2 populations, respectively. The QTLs had different gene effects from over dominance, dominance to partial dominance.