The reconfigurable wheel-track locomotion system integrates wheels and tracks to improve the efficiency and maneuverability of the vehicle. It can dynamically switch between the two locomotion modes based on road conditions, greatly enhancing the vehicle’s adaptability to the environment. Therefore, it has become a hot topic in special ground mobile platforms. This paper first proposes a distributed driving mobile platform. Based on the equivalent reconfiguration principle, a reconfigurable wheel-tracked locomotion system is designed which can transit between wheel mode, half-tracked mode and full-tracked mode. Then the basic structure of its mechanism, reconfiguration principle, and a method for track design are discussed. To minimize the required force capability of the electric actuator of the deformation mechanism, an optimization model for the hinge joint location of the actuator is established considering structure constraints. A Nonlinear programming by quadratic Lagrangian (NLPQL) was adopted to solve the constrained optimization problem. A finite element method (FEM) model was then established to verify the accuracy of the theoretical model. The results indicate that the relative error of actuating force between the theoretical model and the simulation is 13.5%. The optimized actuation mechanism can fulfill the reconfiguration function of the mobile platform. Finally, the mobile robot was built according to the optimization results and an experiment was carried out to test the pivot turning and mode transition functions of the robot. The robot was able to transit between the three modes while it’s in motion, which reveals the feasibility of the reconfigurable system and verifies the optimization model.