In order to prepare high performance polyurea repairing material and verify the waterproof performance of polyurea material， the preparation and performance of polyurea repairing material for concrete building cracks in water transmission channels were studied. A component was obtained by mixing dehydrated water polyol and isocyanate， B component was obtained by mixing 4，4 ''-bis-butylaminobenzene methane and additives， and polyurea material was obtained by mixing A and B components to repair cracks in concrete buildings in water conveyance channels. The optimal reaction temperature and reaction temperature were determined by isocyanate group （NCO） detection. The mechanical properties and hydrostatic impact resistance of concrete repaired with polyurea were analyzed. The experimental results showed that with the extension of reaction time， the NCO mass fraction in the polyurea material exhibited a decreasing trend and then tended to stabilize， with 3 h being the optimal reaction time. As the reaction temperature gradually increases， the mass fraction of NCO shows a decreasing trend， and the reaction of isocyanates is most ideal at 85 ℃. Based on the above results， it can be concluded that polyurea materials have significant effects in repairing concrete cracks， effectively maintaining and improving the compressive strength and ultimate strain performance of concrete. Choosing the appropriate coating thickness is crucial for wider cracks， among which the repair effect is more excellent when the coating thickness is 4 and 6 mm.