【Objective】Strength and elongation variation among different silkworm(Bombyx mori) varieties were studied to provide references for screening breeding materials of silkworm. 【Method】Two grains with identical cocoon width of48 varieties of silkworm cocoon were selected. Strength and elongation of per hundred HUI at the same place in cocoon filament were tested. Using SPSS 17.0 software, breaking strength, breaking elongation and the intensity of cocoon filament were compared among cocoon filament of differen...