The cervical secretion changes periodically, and the secretion during ovulation is abundant, thin, transparent, and pulpy. Women’s cervical mucus under the influence of ovarian sex hormones will occur cyclical changes, due to the influence of estrogen levels, so that the cervical mucus secretion increases during ovulation, is thin, transparent, elastic, easy to be filamentous, and the degree of filamentation can reach more than 10cm. At this time the cervical mucus for smear examination, after drying can be a typical amniotic plant leaf-like crystals, after ovulation under the influence of progesterone, the mucus secretion is reduced, the nature of the turbid, viscous, easy to break the filament. Therefore, ovulation can be determined according to the cyclical changes in cervical mucus.