The icebreaker needs to adjust the ship's longitudinal attitude to accomplish icebreaking during missions. To accomplish the rapid longitudinal adjustment of the ship, a multi-medium method is adopted to complete the ballast/deballast process for the fore and aft tanks. The ballast process is based on a hybrid method using ballast pumps and gravity flooding, while the deballast process is based on a hybrid method using ballast pumps and air compressors. For the ship's ballast/deballast system, a network model for the longitudinal attitude adjustment is established based on the designed multi-medium ballast/deballast method, considering both the fore and aft tanks. Simulation analysis shows that compared with the pure ballast pumps, the multi-medium method increases the ballast process speed by 4% and the deballast process speed by 25.6%. The multi-medium ballast/deballast method can greatly shorten the time required for rapid longitudinal attitude adjustment for icebreakers, thereby enhancing their operation flexibility.