In a large monitored area, the static sensors are deployed by random. It is obvious there are coverage holes and a coverage hole can be polygonal. Because a polygon can be decomposed into a piece of triangles, triangles are considered, and the three nodes of triangles are the static sensors deployed randomly. This paper presents an efficiently deployment algorithm which is based on the coverage hole is a triangle. The triangle is cut into small triangles which contains at least one interior angles is equal to 60°. These small triangles with 60° angle can be guaranteed full coverage, and the rest area of the triangle is still a triangle. Continue the cutting until the triangle is small enough that the sensors on the three nodes can fully cover the area. As a result, the coverage hole of triangle can be full coverage. Beside, the x-y coordinates of each deployed sensor can be deduced.