Abstract: In order to study the influences of temperature on the fracture diffusion characteristics of expansive polyurethane polymer grouting materials, a plate fracture grouting model test device is designed. With a polyurethane polymer slurry applied in engineering as the research object, a series of polymer grouting tests are carried out. The diffusion characteristics of polymer slurry in plate fractures under different slurry preheating temperatures, ambient temperatures and grouting amounts are tested. The changes of slurry diffusion rate, slurry diffusion range, and temperature distribution of slurry and fracture wall under different working conditions are obtained. The analysis results show that the preheating temperature of slurry has an important influence on the diffusion process of polymer. Under the same grouting amount, the higher the preheating temperature, the faster the slurry diffusion rate and the earlier the initial gel time. The slurry diffusion range gradually increases with the increase of the preheating temperature. The slurry diffusion radius at low temperatures is significantly lower than the test results at high temperatures. The slurry diffusion process is not synchronized with the chemical reaction process, and the chemical reaction termination time is later than the initial gel time. The slurry temperature firstly rises and then gradually decreases with time, and the change rate is from fast to slow. At the same time, the temperature at the center of the grouting hole is the highest and gradually decreases along the radial reaction. The rising rate and peak value of slurry temperature increase with the increase of the preheating temperature and ambient temperature. There is an obvious heat conduction between the slurry and the fracture wall during the process of slurry diffusion. The test results can be used as a reference for the researches on the polymer fracture grouting mechanism and grouting technology.