With the construction of urbanization, engineering activities often cause the surface surcharge for the existing tunnel, which adversely affects the safety of the tunnel. Taking a water conveyance tunnel in southern Zhejiang as an example, this paper studies the deformation and protection measures of the existing water conveyance tunnel with shallow foundation under the secondary loading on the ground. According to the surrounding environment, stratum and surcharge distribution characteristics of the tunnel, different protection schemes are analyzed, and the tunnel deformation is simulated by finite element method. The calculation results show that protection schemes for the tunnel can meet the requirements, and the research results can provide reference for similar project construction in the future.