Energy efficient operations are essential to increase the lifetime of wireless sensor network. A clustering-based protocol is one approach that reduces energy by a data aggregation. In this paper we present a CETD(Coverage Efficient Based on Time Delay) clustering method for wireless sensor networks. Initially, every node calculates its own delay time depending on its remaining energy. Nodes with higher energy level have shorter delay time. A node declares itself as a cluster head when its own delay time expires. A self-pruning algorithm is adopted to select best candidate nodes to be cluster heads. Our scheme is a distributed approach and works without base station involvement. Moreover, it has low overheads, in terms of message exchanging cost during the clustering. Finally, our method will be compared with LEACH(Low Energy Adaptive Cluster Hierarchy) protocol. The simulation results show that our algorithm CETD increases the life time of the network around triple times longer than L...