The utility model discloses a variable diameter car steering wheel with electronic helping hand switching device, electronic helping hand switching device include electric motor, transmission shaft, bevel gear, left bevel gear and right bevel gear, electric motor sets up in the central department of hand (hold) disc, and electric motor is connected with the transmission shaft, and the transmissionshaft is connected with bevel gear, and bevel gear and left bevel gear and right bevel gear all mesh, bevel gear sets up the breach department at the hand (hold) disc, and left bevel gear and right bevel gear install respectively at the both ends of iron ring fracture, and just left bevel gear and right bevel gear are connected with spring left end, the spring right -hand member of spring respectively, locking hole and locking key cooperation. The utility model discloses an electronic helping hand switching device can realize the direct regulation of steering wheel to make the operation of switch simpler, easy -to -use, the easy realization.