Abstract: To achieve the maximal operation effectiveness of radar sensor in the defence area, and to detect the low altitude object, it is necessary to meet netting strictness and continuity of detection. Gridded GT search is an approach of radar netting. A method is proposed to solve the problem of how to locate optimally the different radars in a radar network to detect the aircraft of exceedingly low altitude. For optimal radar positions of all kinds of radars and penetration route of low altitude objects, this approach proves to be effective.