Based on a semiphysical range extender experimental system, the control strategies of both start/stop and power following of range extender were optimized. Results show: with the increase of motor dragged torque and dragged end speed, the time of start process decreases to 1.01 s, the number of ultrafine particles for warm start is about 2.0×108 per cm-3; during the engine stop with load from generator, the speed fluctuation decreases obviously; with the fast start and the increase of rise limit for range extender output electric power, the bus power performance is improved; the number of ultrafine particles is about 2.5×108 per cm-3 during swithover process; the power output of engine speed control method is smoother compared with the generator speed control method, but tends to deviate from the optimum fuel consumption curve.