Abstract: A folding menstrual cup comprising an outer cup body with a top accommodating cavity formed therein and a round opening provided on the top thereof and the bottom thereof being connected with a flow guiding pipe via a folding part at the side opposite to the opening; a flow guiding pipe providing with a pipe orifice communicating with the top accommodating cavity and a valve controlling communication to the pipe orifice; and a folding part being capable of protruding upward and enabling the top end of the flow guiding pipe to extend into the top accommodating cavity along with the folding part, and capable of straightening downward thereby a bottom accommodating cavity is formed inside the folding part. When in use, the folding part extends into the top accommodating cavity of the outer cup body and is placed in a body.