The article explains that the silkworm is bred worldwide only as first-generation hybrids for maximum heterosis. The study supports the idea that the effect of heterosis will be significant if the breed components of the created hybrids have outstanding properties. Therefore, the selection of breeds with certain characteristics necessary for silkworm breeders in the future is very important. It is equally important that these characteristics are as high and stable as possible. For this, breeding work is carried out with component breeds aimed at improving certain characteristics. In this study, the selection is aimed at the reproductive properties of breeds. Selection and breeding work for three years has seriously changed some of the indicators of Gren. It has been demonstrated that targeted selection to improve the reproductive performance of breeds I-120, Chinese 108, MG, Ipakchi 2, leads to an increase in the number of normal eggs in the clutch and to a decrease in physiological marriage.