The utility model relates to a test bed for a hoisting speed reducer of a crane truck. The test bed includes a base, a motor sliding screw device, and a device for supporting a trial-coiling drum. The motor sliding screw device includes a bearing box, a guide groove and a sliding plate, wherein a rectangular nut arranged in the bearing box is welded at the bottom of the sliding plate, a motor is fixed on the sliding plate, and a coupling of the trial-coiling drum is connected on an output shaft of the motor; an I screw rod extends into the inside of the bearing box and is matched with the rectangular nut, a left bearing pedestal and a right bearing pedestal for supporting the I screw rod are arranged in the bearing box, and a left crank is arranged at the external end of the I screw rod; and the device for supporting the trail-coiling drum includes a bearing pedestal for supporting the the trail-coiling drum and a supporting shaft, wherein the supporting shaft is connected with an II screw rod penetrating a tailstock, a right crank is arranged at the outer side end of the II screw rod, a locking screw is arranged on the tailstock in the radial direction, and the tailstock is fixed on a support through a left bracket and a right bracket. The test bed can effectively simulate the installation and the bearing of a winding-drum and speeder-reducer assembly on the crane truck, and assess and judge the assembly quality of the crane truck; and the test bed has a simple structure and is convenient to operate.