According to the requirement of projectile long-travel and heavy-load automatic loading, a chain rammer with compact structure and forced ramming is designed. Based on virtual prototype technology, the virtual prototype model of the chain rammer is built. Adding driving according to the driving motor output characteristic, the dynamics simulation of the work process of rammer is carried out and the stability of chain drive ramming is analyzed. The results of simulation show that the projectile is stable in the forced ramming travel, the projectile at the end of the ramming can overcome the heavy load and accurately pushed into the chamber at a certain speed, the values can meet the requirements of automatic loading, and it is proved that the design is rationality.