Intersymbol interference(ISI) is an important factor which affects the performance of communication systems. To achieve highspeed digital transmission and reliable communication, an equalizer can effectively eliminate ISI caused by band-limited channel or multipath. In this paper, we introduce an adaptive H¡Û equalizing algorithm. Different form conventional recursive least square filtering algorithm, the adaptive H¡Û filtering algorithm is a worst case optimization. It can minimize the effect of the worst disturbances (including input noise and modeling error) on the equalization error. It has been proven that the adaptive H¡Û filtering algorithm has the advantage of reduction of sensitivity to modeling error and suitability for arbitrary ambient noise over RLS algorithm. However, the computational burden of the H¡Û algorithm is enormous. To reduce the computational complexity, the subweight partition technique is employed to the H¡Û algorithm. Computer simulation also shows that the H¡Û algorithm can reduce the dynamic estimation error resulting from subweight partition. Finally, in order to overcome multiple access interference, interchip interference, time-varying effects from the channel and computational complexity, the H¡Û algorithm with subweight partition (termed H¡Û-based) is then further extended to the multiuser detection in code division multiple access (CDMA) system. Simulation results are presented to demonstrate the advantage of the H¡Û-based equalizing algorithm.