Respect to the character that the gearbox shifting resistance exist in the fourwheel minitype agricultural tractor is timevarying and nonlinear and the special requirement that the gear shift lever has to be released after shifting, this paper designed a novel gear shift mechanical arm for tractor robot driver. This manipulator is joint type. According to the manipulator’s operating characteristic, this paper applied D-H method to establish the coordinate transformation matrix. Based on the kinematics analysis on the manipulator, Lagrange equation was used to simplify kinetic model of the manipulator. SolidWorks and ADAMS were applied to establish the virtual prototype model of the manipulator and to do kinematic and dynamic simulation respectively. In order to guarantee the smoothness of shift, the distance between the terminal of the manipulator’s actuator and the gear shift lever of the tractor was set to less than 50mm. The absolute value of terminal actuator’s minimum jitter speed during shift was optimized as the objective function. The target function is optimal when the length of shift manipulator is 220.0mm and the height of the terminal is 393.25mm. After optimization, the jitter speed fluctuation is 28.18% less than before. The rate of change of average displacement and average acceleration are 49.55% and 52.05%. At the same time, the peak value of the displacement, velocity and acceleration are 60.22%, 66.24% and 81.66%, respectively. Through the simulation, the optimization of the parameters of the manipulator, the rationality and the scientificity of the model are verified. Finally, through the experiment on gear shift mechanical arm on JINMA 300E tractor, the result shows that the gear mechanical arm can realize the goal to shift different gears smoothly. In addition, the design of the gear mechanical arm can complete some complicated actions of tractor’s driver. Thus, the gear shift mechanical arm has excellent engineering and application value.