The invention provides an entrance ring road self-adaptive control system and a method, which belong to the technical field of intelligent traffic signal system control. The system of the invention comprises traffic detection equipment, traffic control equipment and a communication module, wherein the traffic detection equipment comprises a queuing detector, an upstream detector, a downstream detector and an abouchement detector, and is used for detecting and collection traffic flow data, the traffic control equipment comprises a ring road controller and an entrance ring road signal lamp, and is responsible for controlling the entrance ring road traffic flow rate, and the communication module is used for communication. The system and the method of the invention can response to the traffic flow rate change on a high-speed road, and can automatically select different control methods according to the vehicle flow rate at major trunk roads and at entrance ring road parts. In addition, the hardware of the ring road controller adopted by the invention is simple and is easy to be realized, the development cost is low, and the application range is wide.