Servo mechanism fault of engine brings challenge to the reliability and safety of attitude control system for the new generation launch vehicle, a research on control reconstruction strategy is needed urgently. Aiming at this problem, a control allocation method for the deflection angle reconstruction was proposed. The problem of deflection angle allocation under servo mechanism fault was transformed into the problem of 1norm single objective constrained optimization, and then it was translated into the standardized linear programming model solved by simplex algorithm finally. Simulation results show that the attitude control system can be completely reconstructed by the proposed method under servo mechanism fault, each deflection angle does not reach its saturation value, so the validity of the method is proved.