Wireless sensor networks (WSNs) have been widely studied and usefully employed in many applications such as monitoring environment, embedded system and so on. In WSNs, substantial nodes are deployed randomly over the entire desired area; therefore, the sensing regions of different nodes may be partially overlapped. This is referred to as the sensing coverage problem. In this paper we first define a maximum sensing coverage region problem (MSCR) in WSNs and then solve the problem by the proposed algorithm. In our method, the maximum monitored area fully covered by a minimum active sensors. The main design features are: selecting a small number of delegated sensor nodes by identifying and removing redundant nodes in high-density networks and assigning them an off-duty operation while guarantees the whole area is k-covered, to make sure all events occurred in that area can be accurately and timely detected. We apply the proposed algorithm to improve LEACH, a hierarchical protocol for WSNs and develop a simulation program to evaluate the performance of the algorithm.