The invention discloses a self-adaption forced speed limit system based on real-time road information and a control method thereof. The system is in tandem connection with a speed limit controller on a signal line between an accelerator position sensor and an ECU, the speed limit controller is connected with a smartphone through a bluetooth module, the speed limit controller is further connected with a vehicle speed sensor, the smartphone gets accessed to an electronic map database through a mobile communication network, obtains a vehicle speed limit value VS of a road segment where the current GPS geographic position is located and transmits the vehicle speed limit value VS to the speed limit controller through the bluetooth module, and the speed limit controller changes an accelerator signal transmitted to the ECU according to the current vehicle speed V detected by the vehicle speed sensor and the vehicle speed limit value VS of the road segment where the vehicle is located, so that the forced speed limit control is achieved. The system has the advantages of being simple in system structure, easy to achieve, low in fabrication cost, safe and reliable, and no other equipment is required to be installed on the road.