The key failure mechanism of concrete crack repair system is the poor compatibility between repair material and substrate concrete. With three different types of repair materials, i.e., the cement paste, straight polymer and polymer cement paste, the mechanical compatibility of concrete crack repair structure was studied by a series of mechanical tests. By comparing the results of the shear tests, splitting tensile tests, flexural strength tests and composite beam flexural strength tests, it was found that the composite beam flexural strength t...