Polyurethane porous elastic mixture (PPEM) is composed of polyurethane adhesive, rubber particles and aggregate. Compared with ordinary asphalt mixture, PPEM has the characteristics of large void ratio and high content of rubber particles. Because the PPEM is a macroporous structure, the rainwater is easy to flow into the pavement in rainy days, and then cause water damage. Based on the immersion Marshall test, freeze-thaw split test and immersion dispersion test, the water stability of polyurethane mixture under three conditions of different polyurethane binder, different rubber particle content and different gradation was tested. The results show that the water stability of porous elastic mixture with different polyurethane binder is compared, PU-III porous elastic mixture has the best water stability and PU-IV porous elastic mixture has the worst water stability; With the increase of rubber particle replacement amount, Marshall residual stability and freeze-thaw splitting strength ratio of PPEM increase gradually, which shows that the addition of rubber particle is beneficial to improve water stability of PPEM.The correlation between the void fraction of the gradation used in PPEM and its water stability is negative, the water stability decreases with the increase of the void fraction.