There have been large amounts of sensor network in state-owned grain depots nowadays, and wireless sensor network based on clustering method is its direction of development. However, there has been a problem that cluster heads have a heavy burden due to transmitting mass data, which finally leads to failure of cluster heads because of energy depletion and generation of a coverage dead zone in the wireless sensor networks. We proposed an improved method for coverage conserving routing algorithms to try to solve the problem. For single hop communication, we selected cluster heads according to redefined coverage redundancy; and for multi-hop, we regarded a cluster head with higher coverage redundancy in father nodes as a route for the next hop. By comparing with LEACH-Coverage-U algorithm, simulation results show that, the method proposed in the paper can reduce energy consumption of the network effectively and improve network coverage markedly.