Abstract: The slow resilient PU foams with high loadings of coffee grounds were prepared by a reactive blending method, and their slow resilience performance, mechanical properties, thermal insulation and foaming behaviors were investigated. The results indicated that the hydroxyl groups on coffee grounds could react with isocyanate groups of MDI, but the foaming reaction was inhibited, resulting in a decrease in the amount of foaming gas. In addition, the cellular structure and foaming properties of the PU foams were greatly influenced by the addition of coffee grounds. With the content of coffee grounds as high as 40 wt%, the open cell ratio of the PU foams decreased from 57 % to 15 %, whereas their tensile strength and moduli were improved to 0.15 MPa and 33.5 MPa, respectively. Moreover, the thermal conductivity of the PU foams decreased to 0.050 W/（m·K）, and their resilience time exceeded 3 s at 37 ℃. The addition of coffee grounds could generate a positive effect on the cellular structure and performance control of low-resilient PU foams.