In the wharf reconstruction project，the interface shear strength between existing concrete and new concrete is the key factor affecting the mechanical performance of the reconstructed element. However，there is no definite calculation method or requirement in the Chinese concrete design code. We combine with the example of wharf element reconstruction under the heavy load，summarize the influence factors of interfacial bonding strength，such as the concrete strength grade of existing and new concrete，reinforcement ratio of interface，interface roughness，interface agent and mixing fiber in concrete，compare the calculation methods of shear strength for the interface between existing concrete and new concrete in American code and European code，and propose the suggestions for construction details of interface treatment between existing concrete and new concrete in reconstruction project.The results show that the calculation formula in BS EN 1992-1-1 is economical and reasonable，and it is recommended to use.