The invention belongs to the technical field of pavement and maintenance of roads and bridges, and discloses a method for paving an assembled bridge deck of a long-span steel bridge. The step of surface; the step of processing the steel bridge deck matched with each grid of the modularized steel bridge deck; the step of hoisting the steel bridge deck on the modularized steel bridge deck and fixedly connecting with the steel box girder. The pavement method of the present invention has the advantages of factory production and molding, excellent quality and high precision, can avoid the defects of traditional steel bridge deck pavement, is simple and easy to implement, improves the efficiency of modular construction, shortens the cycle, and distributes human resources evenly. There is no cross-interaction in the process, and the proposal of the assembled steel bridge structure solves the integrity of the bridge deck, the stability and comfort of driving after block installation, the sealing of the joints, and the coordination with the deformation and stress of the steel box girder structure, etc. series of questions.