The present invention provides an annular forging boundary dimension detection system. The annular forging boundary dimension detection system includes a boundary dimension detection device and a detection experiment device; the boundary dimension detection device includes a box body, a laser scanner, a power supply module, a controller and a data transmission device, wherein the laser scanner and the power supply module are arranged in the box body; the output end of the laser scanner is connected with the input end of the data transmission device; the output end of the data transmission device is connected with a remote control device; the power supply module supplies power for the laser scanner; and the detection experiment device comprises a simulation looping type rolling mill, a frequency converter and a driving device. According to the annular forging boundary dimension detection system of the invention, the simulation looping type rolling mill is adopted to realize the rotation of an annular forging, so that the experiment device can simulate the actual rolling condition of the annular forging, and therefore, dimension detection on annular forgings with different dimensions can be realized. The chassis of the simulation looping type rolling mill of the annular forging boundary dimension detection system is provided with movable supporting roller devices and rolling wheel devices, and the main shaft of the simulation looping type rolling mill is provided with an adjustable fixing device, and therefore, adjustment can be performed according to the dimensions of detected annular forgings.