Provided is a rear suspension mounting structure for an electric vehicle, which can reduce the overall weight and can enhance steering stability by forming a torsion beam and a trailing arm using different materials. In one embodiment, the rear suspension mounting structure includes a hub fastened to the center of a wheel, a trailing arm including a housing producing an internal space and an arm bush extending to one side of the housing, a torsion beam bolt-coupled to the arm bush through a coupling plate, a motor coupled to the internal space of the housing and supplying a driving force, a motor cover provided in the internal space of the housing, and a driving speed reducer provided at the outside of the motor cover in the internal space of the housing, wherein the torsion beam and the trailing arm are formed using dissimilar metals.