The invention relates to an assembled tie for shield construction and a construction method thereof, belonging to the technical field of tie pavement in shield construction. The assembled tie is formed by splicing two trolley ties and a slag car tie; the baseplate of the assembled tie is cambered; and the existing joist steel ties are replaced by a cambered right-angled triangle plate and a trapezoidal plate. The assembled tie has the advantage of light weight and the like, is easy to stack, and can protect shielded duct pieces. In the construction process, the trolley ties at the back of the trolleys, which are not used any more, are continuously disassembled, thus improving the use ratio of construction members and effectively reducing the construction cost. The assembled tie and the construction method thereof can be widely applied to installing mechanical ties in the process of the shield construction.