The invention relates to a control device of an automotive electric eddy current retarder. The control device comprises a central processing unit (1), an AD module (2) used for collecting various control signals, a temperature module (3) for measuring the temperature of a electric eddy current retarder body, a keyboard module (4) used for the gear position selection, a speed module (5) used for measuring the speed of the vehicle, a driver module (6) used for driving a self-generating generator and two groups of power source of a storage battery, and a retarder coil (8), wherein, the input interface of the central processing unit (1) is respectively connected with the AD module (2), the temperature module (3), the keyboard module (4) and the speed module (5), and the output interface of the central processing unit (1) is connected with the retarder coil (8) through the driver module (6). The control device has the advantages that the structure is simple, the volume is small, the mass is less, and the operation of the retarder can be automatically adjusted under different vehicle conditions. The control device can expand the active region of the retarder to the low-speed section, and the supporting to the moment of the retarder by the road surface can be always maintained. The invention is a control device of the automotive electric eddy current retarder which has the advantages of skillful design, good performance, convenience and practicality.