An electric motorcycle includes a transmission gear set mounted in a gearbox housing and having a power input shaft inserted through a middle block of the gearbox and a power input pulley mounted on the power input shaft, an electric motor mounted on one side of the middle block and having a motor pulley mounted on the motor shaft thereof, and a transmission belt coupled between the motor pulley and the power input pulley for enabling the electric motor to rotate the power input shaft of the transmission gear set through the transmission belt, a gear shift pedal and a gear shift axle for gear shifting, and a speed output chain gear mounted on an output shaft of the transmission gear set and driven by the output shaft to rotate the rear wheel of the electric motorcycle through a chain.