Abstract: In order to solve the problem of throttling failure caused by high degradation rate during the operation of the soluble Cava outlet, by modifying the surface of soluble magnesium alloy used in Cava, the microstructure and phase composition of the surface modified magnesium alloy were characterized by Sem, XRD and FT-IR, the mechanical properties of surface modified magnesium alloy and its corrosion resistance in simulated well fluids with different pH values (3,7.2,9) were analyzed.The corrosion potential of the modified magnesium alloy in the simulated well fluid with different pH values is positive shifted by about 1.1V, the corrosion current density is reduced by 3 orders of magnitude, and the degradation rate is reduced by about 6.44mm/y; Compared with the simulated well liquid with pH of 7.2, the charge transfer resistance Rct of the surface modified magnesium alloy in the simulated well fluid with pH of 3 decreases from 9.13×10⁶ Ω·cm² to 1.91×10⁶ Ω·cm². The results show that the corrosion resistance of the modified magnesium alloy in the three pH simulated well fluids is significantly improved, but the corrosion resistance in the acid simulated well fluids is the worst. After four months of on-site application, the lower soluble throttles in the Cava river delta have met the expected delivery and salvage requirements. The research results provide theoretical and experimental references for the use of soluble slip lower seats in the production of throttling devices.