To slove the missile body parameter identification problem, taking the missile axial overload as measurement variable, thrust correction coefficient and resistance correction coefficient are designed on the basis of thrust data in the engine ground ignition test and aerodynamic data in missile wind tunnel test. And missile body parameter identification model of least square method is established, respectively for launch speeding state, constent-speed flying state and sliding state with no thrust. The problem of the traditional least square identification equation is solved, and the simulation results proved the effectiveness and correctness of the algorithm. This algorithm is very suitable for missile engineering development.