The general combining ability (GCV), the specific combining ability (SCA) and the reciprocal combining ability (RCA) effects wereobtained by 8$ imes$8 diallel crosses of the silkworms with four Japanese races and four Chinese races, total eight lines. The result are as follows ; 1. The general combining ability (GVA) effects appeared high significant level in the total and the fifth instar periods (TP, FP), a female and a male cocoon weights (FW, MW), a female and a male cocoon layer weights (FL, ML) and a female and a male cocoon layer ratios (FR, MR). Only the reciprocal combining ability (RCA) effects appeared high significant level in the total and the fifth instar periods (TP, FP). 2. The Japanese original silkworm lines varied in the general combining ability effects from -0.864 to 0.578, and the Chinese original silkworm lines did in ones from -0.570 to 1.018. 3. The specific combining ability effects of the silkworm lines made in order of the crossing types of JL (Japanese lines) $ imes$CL (Chinese lines)>CL$ imes$JL>JL$ imes$JL> CL$ imes$CL in a total cocoon weights and a cocoon layer weights. 4. The reciprocal combining ability effects of the silkworm lines was in order of the crossing types of JL$ imes$CL>JL$ imes$JL> CL$ imes$CL>CL$ imes$JL in a total cocoon weights and cocoon layer weights.