Hydraulic lift device of ram mechanism of self-propelled gun is used to lift projectile from the bottom of gun bogle to its launching height. Aimed at this system required of good stability performance with its characteristics of parameters and interference force varying through the whole movement process, the H∞robustness controller was designed. The robustness of system was verified after the controller added by using a μ-synthesis analysis. Simulation and experimental results show that a H∞ controller added system is highly robust against variations in parameters and loading, and effectively improves tracking performance to input signals.