Due to the dynamic topology of the wireless Ad Hoc network, the existing unicast routing protocol mainly applies the expensive flooding to find or maintain the path between source and destination. This essay, from the collaborative work of network layer and overlay layer, put forwards the hybrid unicast routing algorithm AHR based on overlay network. Under the overlay network technology, AHR adequately takes the routing information of network layer as a kind of support, using global index function of overlay layer coordinately. It not only quickly guides the packet to reach destination, but avoids expensive cost of flooding route discovery and effectively reduces the route maintenance overhead. The algorithm is analyzed and proved to have better performance through experiments.