During the long-term storage of weapon launchers, creep will occur over time. The long-term storage of weapons and their launch process are simulated based on the finite element method to study the influence of creep on weapon launch. Meanwhile, the effects of launch angle and storage time on the creep in the launcher and the weapon launch process after storage are analyzed. The results show that the launcher ends the transient creep stage after about one year during storage and enters the steady-state creep stage. The weapon is deflected by the creep of the bottom carrying device, and the deflection is positively correlated with the launch angle and storage time. The weapon launched after long-term storage deviates from the initial launch axis, and the influence of creep on the launcher structure and the launch process of the weapon during storage cannot be ignored.