The increasing number of capillaries on the legs generally refers to capillary dilatation, the cause of which is related to genetics, hormones, viral infections, pregnancy and other factors. 1. Hereditary factors: capillary dilatation has a certain genetic susceptibility, if both parents suffer from capillary dilatation, the chances of their children suffering from the disease will increase. 2. Hormonal factors: long-term use of steroid hormones or estrogenic drugs may induce capillary reflux disease. 3. Viral infections: Viral infections may trigger trichotillomania, and common viruses include EBV. 4. Pregnancy effects: Women in pregnancy may experience capillary dilatation due to increased circulating blood volume. There is no single reason for the increasing number of capillaries on the legs, and patients are advised to go to regular hospitals for relevant examinations to identify the causes.