Abstract: Combining the advantages of steel and concrete, the double–steel-plate composite (DSC) structures exhibit the advantages of high bearing capacity, good seismic performance and durability, and convenient construction, and they have been increasingly used in nuclear engineering projects. The connection between DSC walls and reinforced concrete raft foundation is the key to make full use of the aforementioned advantages. Compared with the traditional embedding connection and anchoring connection, the lap splice connection can greatly improve the construction efficiency, which gains more and more attention. However, there is few research on such connection. Therefore, in this paper, four 1∶2 scaled lap splice connections between double-steel-plate composite wall and RC foundation are designed, and the static monotonic loading tests are carried out. Through the observation of bearing capacity, stiffness, crack pattern and strains of steel plate and rebar, the influences of the arrangement of lapped bars and tie bars on the mechanical performance of the connections are explored. The test results show that this kind of connection can achieve equal strength and shows satisfactory ductility. Transverse bars can control the crack development effectively and improve the integrity of the connection greatly; in addition, the tie bar strain along the lap length is not linearly distributed. The higher eccentricity of the lapped bars, which means larger unbalanced moment between the reinforcement and the steel plate, will result in lager strains of the transverse bars and lower slip of lapped bars. This paper provides experimental basis for the design of lap splice connections.