The invention relates to a modular trolley follow-up power assisting device. The modular trolley follow-up power assisting device consists of a handle, a controller and a modular assembled driving device, wherein the handle and the controller are mounted on a trolley; sensing assemblies for detecting the magnitude of thrust applied to the trolley are arranged in the handle; an output shaft of the modular assembled driving device is connected with wheels of the trolley; the handle is connected with the modular assembled driving device through the controller and is used for inputting signals capable of automatically sensing trolley pushing and pulling states to the controller; the controller controls the modular assembled driving device to drive the wheels to accelerate, decelerate or move forwards at a constant speed; the magnitude of a driving force and a driving direction are controlled in an automatic servo manner so as to control traveling and cornering of the trolley. The pushing and pulling states can be automatically sensed, manual judgment is not required, and the magnitude of the driving force and the driving direction can be controlled in the automatic servo manner so as to control traveling and cornering of the trolley. By the modular design of the power assisting device, the trolley can be modified conveniently.