In the navigation war, the prevention of timing service to adversaries in local area can be realized by turning off all the navigation signals of visible satellites artificially. This study takes turning off the navigation signal for preventing the timing service in local area as an example, describing the simulation process of prevention of timing service by turning off the navigation signal in local area, and puts forward the evaluation method of positioning and timing performance as well. The effect of preventing timing service on the performance of global positioning and timing service is analyzed subsequently. The results imply that, with the prevention of timing service in local area by partially turning off the navigation signal, both positioning and timing service are limited to the civilian users around the site, and the accuracy of positioning will become worse in the global area. Moreover, the availabilities of positioning and timing will be decreased in global area under the circumstance of partially turning off the navigation signal for preventing the timing service in local area.