Abstract: Computing the overhead traffic by an effective route metric is the basis for devising route protocols in wireless sensor networks. It was found through experimental study that there are some characteristics in bottom-layer communication link of wireless sensor networks, such as packet lass and asymmetry. However, mast of route metric are assuming that the bottom-layer communication link is ideal at present. So, the moment estimate is proposed as a new route metric by computing it between forward and backward packets receiving rates which were measured in the links of wireless sensor network. Then, the conventional AODV protocol is amended that the minimal hop metric in it is replaced by moment estimate. Results of simulation with NS-2 showed that the moment estimate is better than the original minimal hop for end-to-end throughput with packet loss rate greatly decreased.