Based on the idea of using mobile robots instead of farmers to work in the complex environment of farmland and reducing the burden on farmers, a type of reconfigurable mobile robot with wheel/track shape was proposed. Four wheel/track configurations of the same structure were adopted to reconstruct the walking unit and the vehicle body, which had two walking postures, a wheel type and a crawler type, to adapt to the complex terrain in the field. The reconfigurability of the wheel/track motion pattern was achieved by the wheel/track shape conversion device. The mathematical model of the walking unit was derived, and the relationship between angle of swinging rod of robot and height h of step and range of slope that can climb can be obtained when the walking unit robot overcame the obstacle. The virtual prototype and simulation environment of the walking unit were established in Simulink and ADAMS, and the prototype was developed. And calculated by the error formula, the simulated value and the theoretical value of the error were between 10-8 and 10-6. The driving torque error between ADAMSs simulation and theoretical values was only 126×10-5N·m, which verified the correctness of the mathematical model and obtained the driving torque required by the robot during the wheelshifting process, and provided a theoretical basis for the subsequent experimental research of this type of robot.