To determine fire unit selection and fire time of ship borne common-frame weapons, the concentric canister launcher controlled by launch order is taken as the object, and a new time coordination method is proposed. The time coordination model is built based on combustion gas exhaust, initial trajectory intersection and so on, and core concept of ant colony algorithm is brought in, adjusted and modified to solve the model. The model and the algorithm are verified with an arithmetic example. The results show that the method could offer optimized time coordination scheme to make fully effectiveness of the launcher extremely.