Abstract: A routing protocol based on gradient and cluster in wireless sensor network is analyzed. An energy-efficient gradient-based clustering routing protocol (GBCRP) is proposed and evaluated. The new protocol combines the advantages of gradient and cluster. It saves the energy and improves the reliability by the technologies of clustering, creating gradient based on the hop, key nodes transmitting and the adaptive power optimal routing of cluster header nodes. Simulation results show that the new routing protocol provides longer lifetime and higher reliability.