Static balance is the initial condition of catapult launch dynamic analysis, and the foundation of establishing the catapult launch model. Carrier, aircraft and landing gears, etc. are considered as multi-motion bodies that have their own masses, and the coupling relationships within these multi-motion bodies are also analyzed. The six degrees of freedom model of carrier-based aircraft is established in the condition of static balance, with the influences of carrier movement, deck wind and the airflow interference on aircraft considered. This model is applied to calculate and simulate the static balance of aircraft in different situations. The simulation and calculation results are consistent with the actual situation, which lays a foundation of dynamics analysis on carrier-based aircraft catapult launch with the six degrees of freedom model.