The traditional diagnostic method is B-ultrasound or diagnostic scraping. B-ultrasound is a non-invasive test, but the leakage rate is high for two reasons: firstly, it is not easy to distinguish small endometrial polyps from the thickened endometrium in the middle and late menstruation; secondly, it is difficult to distinguish large endometrial polyps from other occupying lesions in the uterus. Hysteroscopy is the only diagnostic method that can examine the physiological and pathological changes of endometrium under direct vision. It can make accurate judgment on the site, size and number of endometrial polyps, and scrape a little endometrium for pathological examination to evaluate the endometrium of the uterus. The time of hysteroscopy should be half a month before menstruation, preferably 3~7d after menstruation, which can reduce the infection on one hand, and more importantly, the endometrium is at the early stage of hyperplasia, which can reduce the influence of endometrial hyperplasia on the diagnosis of endometrial polyp, and thus improve the diagnostic accuracy.