In wireless sensor networks, the power resource of

each sensor node is limited. Minimizing energy dissipation and

maximizing network lifetime are important issues in the design

of routing protocols for sensor networks. In this paper, Cluster

routing protocol LEACH (Low-Energy Adaptive Clustering

Hierarchy) is research and improved. We extend LEACH

stochastic cluster-head selection algorithm via changing the

round time According to the situation of sensor network. It is

named Variable-round LEACH. The result simulated in NS2

shows that the energy is significantly reduced and the lifetime

of the whole network is increased compared with the previous

routing algorithm for the sensor networks.