The invention discloses a variable idling start test bed for an electric car transmission system, and the test bed comprises a control power supply, a DC motor, a shaft coupler, a rotation speed and torque sensor, a clutch, a spline shaft, a brake disc, mechanical braking devices, a DC generator, and a resistor box. The control power supply is connected to the DC motor, and the rotation speed and torque sensor is connected with the DC motor through the shaft coupler. An output shaft of the rotation speed and torque sensor is connected with a driving disc of the clutch, and a driven disc of the clutch is connected to a side of the spline shaft, wherein the other side of the spline shaft is in series connection with the brake disc. The mechanical braking devices are disposed at two sides of the brake disc. The DC generator is connected with the shaft coupler, and is connected to a test bed transmission system. The resistor box is connected to an armature loop of the DC generator in a series manner through a wire. The clutch is disposed in a transmission shaft system in fixed connection with a conventional electric car test bed, thereby forming a flexible connection mode of a transmission system. Moreover, the idle speed can be adjusted, the loading is flexible, the operation and control are simple, and an impact-type load is easy to simulate on the test bed, and the test bed is suitable for actual driving and road conditions.