Rear suspension mounting structure for electric vehicle

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 based on a coupled torsion beam axle (CTBA) method includes a hub fastened to the center of a wheel to be rotatable, a trailing arm including a housing producing an internal space and an arm bush extending to one side of the housing and coupled to the vehicle body, 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 sealing the motor from the outside of the housing, and a driving speed reducer provided at the outside of the motor cover in the internal space of the housing, coupled to the hub and reducing the output driving speed in a constant gear ratio, wherein the torsion beam and the trailing arm are formed using dissimilar metals.