To promise low energy consumption for wireless sensor network routing, a number of routing protocols have been published. A novel routing protocol called BeamStar was proposed in [6]. In BeamStar, each base station uses a directional antenna with power control to assist locating sensors. It shifts the burden of network control and management from resource-limited sensors to resource-abundant and more sophisticate base stations, but still has three serious problems. The different size between the nearer and farther region, base station΄s scanning time, and a great quantity of inter-node communication all waste precious energy. In the cause of solving these problems, we present a routing protocol, namely Cluster-based BeamStar (CBS), for wireless sensor networks. CBS follows cluster-based structure to decrease the volume of inter-node communication and we have reformed the scanning manner in BeamStar. Our simulations show that CBS is scalable, low-cost, and energy efficient. [ABSTRACT FROM AUTHOR]