The invention relates to an automatic assembly technology, and aims to provide an automatic flexible assembly system based on distributed mobile platforms and a control method. The system is providedwith a plurality of mobile platforms, and a plurality of workstations are arranged along a transport line; each mobile platform comprises a tray, a driving device mounted at the bottom thereof and a distributed controller that can receive wireless signals and is connected to the driving device via a signal wire; the workstations comprise an invalid station, a storage station, an artificial stationand an automatic station; a deceleration sensor, a stop sensor and a trigger cylinder are arranged at each workstation, the sensors are connected to a central controller in a wired or wirelesscommunication mode, and the central controller is wirelessly connected to each mobile platform. Compared with the prior art, the system and the method can realize asynchronous motion and synchronous assembly, greatly improve the flexibility of the transport line, and can meet the requirements of diverse flexible assembly. The wireless communication technology can reduce the cost of the control system andimprove the working efficiency and the maneuverability of the system.