A novel robust approach of speed control was adopted for PMSM during the agricultural electric vehicle’s preshift process. Considering the twogear electric vehicle electric driveline, the gearshift process was studied and the preshift process was introduced, electromagnetic speed synchronization of the driving motor was considered specifically. Based on the structure of the driveline and the agricultural working condition, dynamic modeling was completed. And a nonlinear robust control approach was introduced to complete the robust control task of electromagnetic speed synchronization. The adopted control algorithm was characterized by errorbased and modelbased algorithm inheriting from traditional PID control and robust control. The control algorithm consisted of a modelbased algorithm component, a PD component as a feedback control and a piecewise function component as a robust feedback control, in which the system uncertainties and external disturbance were lumped. These system uncertainties and external disturbance were assumed to have upper bound. Based on the Lyapunov method, it theoretically proved the proposed control algorithm had render uniform boundedness and uniform ultimate boundedness. The effectiveness and robustness of the proposed control method for speed synchronization control of permanent magnet synchronous motor were verified by numerical simulation and bench test. By comparing with the traditional PD control, the proposed robust controller had obvious advantages under the same PD control parameters considering the load fluctuation conditions of agricultural electric vehicles. Average speed synchronization error and standard deviation were obviously better than those of traditional PD control in simulation result， which was 30% better in test result. The precise robust control paved the way for synchronization of synchronizer in the later stage and played an important role in improving shift quality.