For precise threat assessment of attack target, and acquiring best interception efficiency for aircraft carrier formation, establish target threat assessment model for aircraft carrier formation cooperative air defense based on cloud model. Through analyzing air defense threat assessment factor, establish threat assessment index system based on target attack capability, attack intent, attack speed and relative value of the ship. Use different value membership degree of every ship, calculate treat sequence of air attack target to whole formation and carry out simulation verification. The simulation results show that: the model can correctly deal with and effectively integrate data, acquire correct results rapidly and provide a reference for the aircraft carrier formation air defense operation.