The causes of severe oligospermia and hypospermia include, but are not limited to, chromosomal abnormalities, which may be related to the patient’s own genetic problems. 1. Oligospermia: clinically, the causes of most cases of oligospermia are clear, such as chromosomal abnormalities, endocrine diseases (such as pituitary insufficiency, hypogonadism, etc.), immune factors, reproductive infections, cryptorchidism, and temperature effects, etc., but the causes of idiopathic oligozoospermia have not yet been clarified. 2. Weak spermatozoa: the causes of weak spermatozoa are more complicated, including congenital factors (such as chromosomal abnormalities, etc.), acquired injuries (such as exposure to toxic and harmful occupations, testicular injuries, etc.), acute and chronic inflammation of the reproductive system of the male epididymis, vas deferens, prostate, etc. as well as bad habits (such as smoking, drinking, etc.), but for idiopathic weakening of spermatozoa, the etiology of this disease has yet to be clarified. There may be other causes for severe oligozoospermia, and it is recommended to visit the hospital in time.