Abstract: In ad hoc networks, to solve the high level of routing overhead problem while on-demand routing protocols using full-net query flooding during route discovery, a local route discovery algorithm was proposed to reduce the routing overhead. Nodes around every route calculated the minimal hop counts to the destination node based on data packets through the route. When one route was broken, the route discovery request packets would be relayed only by nodes around the broken route in the way of the minimal hop counts decreased, which reasonably restricted route discovery region. The route discovery range would be enlarged by adding hop counts of route discovery request packets relayed by nodes around the broken link, which increased local route discovery success rate. The experimental results by simulation indicate this algorithm could contribute to reducing the routing overhead by about 60%, cutting down the average end-to-end delay by about 70%, and increasing the packet delivery ratio by about 10% at most. In addition, any routing protocol depending on flooding based routing discovery can use this algorithm for performance optimization.