Abstract: The ZZWW 4n female silkworm was obtained of super-cooling. This 4n female was mated to ZZ 2n male silkworm. The expressively of mark gene and the number of sex chromosome in the parents and progeny were observed; the synapsis,distribution and probability of the sex chromosome of ZZWW female silkworm were discussed; and the synapsis,detachment probability of the sex chromosome of zzwwsilkworm female were presumed. We plant to offer the theoretic foundation to resolve the mechanism of the inducement of polyploid silkworm, to prognosticate the expressivity of their progeny and to provide an efficiency wayto study the polyploid practicality.