It is rare for blue discharge to appear in women’s underwear. It is necessary to exclude whether the color of the underwear is staining the discharge or the vaginal inflammation is causing the discharge to be abnormal. The normal leucorrhea in women should be egg white, but when there is an inflammatory infection, it is more common to see yellow discharge or yellow-green discharge, but blue discharge is not seen. The more common vaginal inflammation, including bacterial infection, trichomonas infection and mycobacterial infection, can be treated with symptomatic medication according to the test results. If the results of the routine leucorrhea check are normal, it is likely that the discharge is stained due to discoloration of the underwear, which can be improved by washing the underwear or by wearing white cotton underwear and observing whether the abnormality still exists.