Abstract: Professor Xia Guicheng, a master of traditional Chinese medicine, advocated the "menstrual circle rhythm and menstrual cycle regulation method", which is an inherent theory in traditional Chinese medicine that explains the laws of circular motion and biological clock, and helps to analyze the changes in menstrual cycle and reproductive rhythm. The circular motion is a universal law of the movement of life in the universe. The ancients described the circular motion of the fall, rise, sinking and floating of yang heat related to biological life in nature through the 24 solar terms. The menstrual cycle is the result of a woman's own movement of fall, rise, sinking and floating of yang heat, as well as being influenced by the natural movement of yang heat. There is a corresponding relationship between the menstrual circle rhythm and the circular movement of natural yang heat: yang heat rises to the extreme and then falls, corresponding to the fact that yang accumulates to the extreme and then transforms into yin during menstruation; the decrease of yang heat in the golden autumn corresponds to the disappearance of yang and the growth of yin in the later menstrual period; yang heat falls to the extreme and then rises, corresponding to the fact that yin accumulates to the extreme and then transforms into yang in the intermenstrual period; yang heat rises in spring corresponds to the disappearance of yin and the growth of yang in the premenstrual period. The essence of the menstrual cycle regulation method is to restore the normal rhythm of the body's growth and decline of yin and yang, as well as the rise and fall of movement and stillness based on the menstrual cycle.