Menstrual diarrhea is a common periodic gynecological disorder characterized mainly by loose stools and increased frequency during or before and after menstruation, which seriously affects the physical and mental health of women. “Spleen governs time” comes from “Yellow Emperor’s Inner Canon”, presenting the core ideas of “spleen governs long summer” and “spleen does not govern time”, emphasizing the physiological characteristics and pathological tendencies of the spleen in specific seasons. Based on the connotation of the theory of “spleen governing time”, and in combination with the pathogenesis characteristics of menstrual diarrhea, which is characterized by “spleen deficiency as the root, excessive dampness as the symptom, and aggravation during menstruation”, this paper explores the clinical treatment principles and the application of prescriptions based on this theory, providing new ideas and theoretical basis for the traditional Chinese medicine treatment of menstrual diarrhea.