The invention discloses an assembly trolley for an open-cut subway station formed by assembling prefabricated parts. The assembly trolley comprises a main machine frame and a top assembly frame installed on the main machine frame, the top assembly frame is composed of motion pairs of an upper rack, a middle rack and a lower rack, the three racks can slide in the longitudinal direction and the transverse direction, and assembly of a block C, a block D and a block E of the station can be completed through operation by a hydraulic system. A first-layer rack of the motion pairs of the upper rack, the middle rack and the lower rack controls the height of the block D and the block E, and the motion displacement data are collected through a magnetic resistance type displacement sensor of the PME 12 series. Eight CH6 digital displays are adopted cooperatively, timeliness and accuracy of information transfer are realized, and the work efficiency is improved.