In order to address complex terrain challenges and enhance the stability and load-bearing capacity of wheel-legged robots, a novel two-rotation, two-translation hybrid leg mechanism was proposed. This design features a side-mounted parallel structure as the main component and has undergone simulation analysis of its kinematic performance. The mechanism was based on a (2-RRS-RPS) & R hybrid configuration. A motion screw matrix was established for the mechanism using screw theory to analyze its degrees of freedom. The modified Grübler-Kutzbach formula was then applied to verify these degrees of freedom. Subsequently, the kinematic inverse problem of the mechanism was solved. Based on the solution to the kinematic inverse problem, the achievable workspace was mapped. Adams software was utilized to simulate the motion of a single leg, thereby validating the correctness of the model. Gait planning and simulation for obstacle crossing were conducted to further confirm the robot’s stability and mobility on complex terrains.The results indicate that the mechanism exhibits good motion performance and can meet the requirements for both motion and operational range.