The firing time model of warship formation in coordination air defense is set up for the shortcomings of existing firing time model. First the non-zero shortcut route firing time model of single warship is set up under certain assumptions. Then the firing time of warship formation in air defense is decomposed to the sum of the firing times of ship under attack and adjacent ship. At the same time, the distance of ship prohibit line and target offensive line is studied to optimize the model. Finally, the relation between firing time and other parameters, such as target course angle, interval time and velocity, is simulated. The result of simulation shows that this model can calculate the firing time of warship formation effectively and it also can prove the intercepting effectiveness of warship formation air defense.