Abstract. In the fast frequency hopping system, the diversity combining technique of the receiver can effectively restrain the partial band interference, and it is the key to improve the anti-jamming capability. For the computation and complexity of the maximum likelihood diversity combining algorithm, we allow the reduction of the SNR to a smaller level, then we can use the sum of squares to simplify the approximation. The several maximum likelihood diversity combining algorithms are compared and analysized. It gives the realization process of the simplified diversity combining algorithm, the complexity of the algorithm is greatly reduced, and it is easier to implement on hardware.