The reproductive system of Aegista taiwanica was dissected and compared with allied species in this article. They differ in the number of lobes of glands of the auxiliary copulatory organ, the morphology of accessory-sac of the auxiliary copulatory organ, the ratios of the length of penial sheath/penis and the length of epiphallus/penis. Aegista taiwanica has two lobes of glands of auxiliary copulatory organs, depressed and ellipsoidal accessory-sac of the auxiliary copulatory organ, medium length of epiphallus and short penial sheath.