The invention discloses a cover plate assembly tool for an escalator. The cover plate assembly tool comprises a locating locking device, a centering device, a lower support and an upper support. The locating locking device comprises a crossbeam and a clamping mechanism. The two ends of the crossbeam are each provided with a locating plate. The clamping mechanism and the locating plates are matchedto lock a cover plate. The centering device is movably arranged on the crossbeam. The lower support comprises connecting plates, a support seat and a vertical frame. Skirt boards on the two sides areconnected with the connecting plates correspondingly and detachably. The support seat is connected with the connecting plates and is supported on the skirt boards. The vertical frame is arranged on the support seat and is connected with the support seat. The upper support comprises a connecting part, a clamping mechanism and a lifting mechanism. The connecting part is connected with the upper endof the vertical frame. The clamping mechanism is used for clamping the crossbeam and is connected with the connecting part. The lifting mechanism is used for adjusting the height of the crossbeam andis connected with the connecting part. According to the technical scheme, measurement and adjustment of the cover plate are simplified, installing precision is high, and stable and reliable effects are achieved. The cover plate can be reliably fixed after measurement and adjustment are completed and is not liable to shift, measurement and adjustment of the cover plate do not need to be conductedon an escalator truss, and operation is convenient.