【Abstract】 Handoff block rate is a very important QoS (Quality of Service) indicator in mobile communication. In hard handoff, the conventional method of reducing handoff block is to reserve some channels especially for handoff mobile terminals in the cell or cell group. This is a static method. It can guarantee the handoff successful rate, but in the meantime, some resource of wireless channel is wasted. In this paper, a dynamic reserving channel resource algorithm has been put forward on accessing instantaneous process. It can improve the utility of wireless network resource. In the paper, this algorithm also is tested in simulating experiment. The results show that the algorithm is available.