Abstract: To decrease the severe bit error rate in high data rate HF communication systems when deep fading of ionosphere channel appeared, a novel efficient iterative combining-equalization algorithm is proposed based on minimum mean square error criterion. The algorithm constructs a block-based combining-equalizer and exchanges soft information with soft-input soft-output (SISO) decoder by adding a hard-to-soft information conversion module, and acquires benefits from the joint utilization of the spatial and temporal information. Simulation results show that the proposed algorithm can reduce the receiver bit error rate effectively without notable computational burden increase hence has wide application in high data rate HF communication system.