Aiming at the air combat scenario where the defensive missile intercepts the attacking missile, this paper proposes an optimal cooperative guidance algorithm with two-to-one active defense. This algorithm adds a second defensive missile pair on the basis of the traditional one-to-one optimal guidance algorithm protect high-value target aircraft, and derive the optimal cooperative guidance law in two-to-one combat mode. The simulation results show that compared with the proportional guidance (PN) guidance law, by introducing an optimization index that minimizes the deviation of the relative end intercept angle, the relative distance between the two defensive missiles is kept within a very small range, which achieves a very good effect of coordinated interception, it reduces the energy consumption of defense missile control, thereby verifies the effectiveness and superiority of the optimal coordinated guidance rate.