The invention discloses a roadbed dynamic rebound modulus site testing device and a measuring method thereof. The roadbed dynamic rebound modulus site testing device is composed of a processing devicewith displaying, inputting and storing functions, a measurement and control system, an electro-hydraulic servo loading oil source system, an oil pressure pipe, an electro-hydraulic servo actuator, asupport system, a pressure displacement sensor, a bearing plate, a pressure bearing plate and an increasing weight. The problem that an existing standard detecting method does not consider dynamic loads and does not conform to the actual working state of a roadbed can be solved, and by simulating the traffic load effect of the road surface and measuring the dynamic loads of test points and the displacement value of a roadbed structural layer, the dynamic rebound modulus value of the roadbed structural layer is automatically calculated and generated. The dynamic rebound modulus value of the tested roadbed structural layer can more effectively reflect the roadbed dynamic rebound modulus of the roadbed structural layer under the dynamic load conditions and can also better provide the technical support for road and railway design parameters.