Abstract: In order to obtain low-cost and excellent mechanical properties of polyurethane reinforcement materials for coal mine, the silane coupling agent 3-glycidoxypropyltrimethoxysilane (GPTMS) was used to modify fly ash (FA) and then compound with polyurethane (PU) to prepare PU/FA composite reinforcement material. The compressive strength test results of PU/FA composite reinforced materials modified by GPTMS with different mass fractions showed that the best modified quality fraction was 2.5%. The effect of GPTMS modification on the fracture, bending and bonding properties of PU/FA reinforced material during the curing process was systematically studied, and it was found that the fracture toughness, maximum bending strength and the bond strength of the modified PU/FA composite material increased by 10.1%, 8.8% and 19.3% respectively. Scanning electron microscope was used to analyze the microscopic morphology of the composites, the results showed that GPTMS coupling agent could improve the mechanical properties of PU/FA composites.