The simplified model of concentric canister launcher (CCL) was proposed according to the gas flowing and exhausting process.The gas from the rocket motor nozzle flows through a stage of reducing cross-area and experiences a uniform section frictional pipe flow.A numerical simulation of a certain CCL case was conducted to verify that the simplified theory model was reasonable.Then some structural factors of optimizing design of CCL were summarized and explained how these factors worked from the analysis of the simplified theory model.According to the basic simplified theory model

a convenient and simple method to estimate the smallest size of gap and the additional eject force of missile has been given.And the simplified theory model also can be used to guide and improve the design of CCL.