The hydraulic principle diagram of the subgrade test device, the dynamic pressure cylinder electro-hydraulic servo pressure system math model and AMESim simulation model are provided. Divided the system into two parts of the dynamic pressure cylinder displacement subsystem and the dynamic pressure cylinder output pressure subsystem, on this basis, an adaptive backstepping sliding mode control method was designed: using the double sliding mode structure, constructed separately adaptive sliding mode control for dynamic pressure cylinder displacement subsystem and adaptive backstepping sliding mode control for dynamic pressure cylinder output pressure subsystem, adaptive law of uncertain parameters was provided, and the stability of the method was proved. Finally, applied the method to the dynamic pressure cylinder electro-hydraulic servo pressure system AMESim model, simulation results show that: this method can not only effectively estimate the parameters of the system, achieve accurate tracking of the target variables, have better control and tracking performance compared with integral sliding mode adaptive control (ISAC); but also can effectively reduced the effect of parameter uncertainty on tracking performance, and have good robust performance.