Abstract: The accumulation of fluid in the uterine cavity, known as endometrial cavity fluid(ECF), is easy to be ignored in clinic due to its inconspicuous symptoms and the requirement of ultrasound for diagnosis. Its association with various female reproductive system disorders can significantly impact the physical and mental well-being of women during their reproductive years. Presently, there is limited understanding regarding ECF, and elucidating its origins and associated mechanisms remains a formidable task. This article endeavors to offer a thorough and systematic examination of potential sources and mechanisms underlying ECF, aiming to furnish valuable insights for clinical diagnosis, treatment, and scientific inquiry.