Aiming at the safety hazard of conveyor belt slippage and ' flying car ' caused by excessive gravity component of raw coal in large slope and long distance downward belt conveyor, this paper proposes and designs an anti-flying device based on the concept of top belt drive. The device introduces a central drive mechanism with a ' four-fold reentrant ' winding structure in the upper belt area, and combines the permanent magnet synchronous frequency conversion drive technology and the optimized design of the head unloading and storage bin layout. From the two dimensions of mechanical friction increase and electrical control, the friction envelope angle and equivalent friction coefficient between the conveyor belt and the driving drum are significantly increased. The device can effectively balance the gravity component in the running direction of the conveying system, curb the phenomenon of flying cars from the root, and avoid equipment damage and personal safety accidents.