The invention relates to a bottom leakage-proof conveyor belt of a conveyor belt self-unloading semi-trailer, belonging to the technical field of conveyor belt and self-unloading semi-trailer. The conveying plate of the invention is reliable in sealing at the front and rear overlapping parts, thereby eliminating bottom leakage and avoiding leakage and pollution of dusty water; The conveying plateof the invention is supported on the cross beam of the vehicle frame, and is locked relative to the vehicle body by the locking device, so that the chain does not bear the pressure of loading bulk cargo, and the stress state and the working environment of the chain are improved. During unloading, the front and rear overlapping conveyor plates can share the tensile load of loading bulk cargo, whichcan reduce the load of chain and the load peak value of driving sprocket starting, so that the chain runs smoothly. The locking device of the invention can be locked and sealed, the rigidity of the body is increased, and the stress state and the working environment of the body are improved. The water receiving tank of the present invention concentrates seepage water from bulk cargo into the watercollecting tank, avoiding contamination of the conveyor belt and the environment of the present invention. The protective groove of the invention can be tensioned, accommodates and protects the chain, and avoids the pollution of dust and water raised from the ground.