This paper presents an approximation algorithm of minimum cover set based on pixels of sensing region.The node sensing area is discredited into a series of pixels

and a node is redundancy if all of its pixels are covered by other nodes.So we can get the maximum redundancy node set

and also its complement — the minimal cover set.The feasibility and performance of the algorithm is discussed

correctness of the algorithm was evaluated by experiment.Compared experimental data show that its minimum cover set is equivalent to the CVT algorithm

and its time complexity is superior to the CVT algorithm.