The kernel of a plane simple polygon is a point set in the interior of this polygon

in which any point can be connected to another arbitrary point on the border of the polygon with a line inside the polygon. The character of kernel finds its application in such fields as the positioning of the camera. We propose a new method to calculate the kernel of a single polygon

which can not only judge the existence of the kernel

but also get the point list of the kernel. The given arithmetic is easy to understand and realize

and can be widely applied to such kind of problems.