Oblique vaginal septum is a not very rare genital tract malformation. The clinical manifestations are peculiar, often resulting in delays in diagnosis and treatment. However, it is rarely or not introduced in general textbooks. The definition of oblique vaginal septum mainly includes the following aspects: 1. Double uterus and double cervix, some cases may have single cervix combined with uterine septum. 2. Oblique vaginal septum is different from vaginal septum that divides the vagina into two sides, and also different from vaginal septum that divides the vagina into two sections. Oblique vaginal septum is a membranous tissue covered with vaginal epithelium on both sides, originating between the two cervixes, obliquely attached to the vaginal wall on one side, forming a blind tube to cover the cervix on that side, and there is a cavity between the back of the septum and the cervix, which is the post-septal cavity. 3. Urinary tract malformation, almost without exception, combined with the absence of kidneys and ureters on the same side as the oblique septum. This case was first reported in 1992, but there was no appropriate name, and some named it uterus didelphys with unilateral imperforate vagina. Since the prominent feature of this deformity is that there is an obliquely attached septum in the vagina, it is most appropriately called oblique vaginal septum syndrome.