An improved central speed control mechanism for remote control cars primarily comprises a housing and a cover, which are connectable to each other and are respectively provided with a pivot for connecting to the remote control car at one end and mounting helical gears at the other end. Inside of the housing is provided with a gear set, which comprises a positioning block, a plurality of bevel gears and axles. Axle holes are equally provided on the periphery of the positioning block, whereas a central hole with a cone surface is provided in the bevel gears for matching with the cone surface of the axle which is provided with a positioning pillar at the front end and a cone surface in the middle section. After the axle passes the end of the bevel gear provided with a O-ring through to the axle hole, and a washer is further provided at the rear of the axle to complete the assembly of the whole housing, the plurality of bevel gears of the gear set will engage with the helical gears of the two pivots.