In this paper, we propose a blind-zone centroid-based scheme (BCBS) for solving the coverage problem of wireless sensor network in two-dimensional monitor area. In BCBS the monitor area is partitioned into several Voronoi polygons by using the Voronoi diagram and then each Voronoi polygon can be covered by one sensor. The next work in the BCBS is to obtain the blind-zone in the Voronoi polygon according to the positions of its vertexes in order to construct the polygon, which is approximately the shape of the blind-zone. The centroid of the polygon is then regarded as the candidate target position for the sensor nodes in order to improve the coverage rate. Experimental results show that the BCBS has advantages in the coverage rate, uniformity of the nodes distribution and the efficiency of the nodes coverage over the centroid-based scheme.