Abstract: In order to study the influence of urban grid supervisors in improving the coverage ratio of forest fire monitoring at forest mountain surrounding main city, taking mountain surrounding Kunming main city as the research object, using data such as DEM（Digital Elevation Model）, urban building contour, forest management inventory, iron-tower video surveillance system, fire watch towers and urban grid, after a series of processes, taking viewshed analysis by whether urban grid supervisors participate or not, two coverage range and coverage rate of forest fires monitoring in forest mountain surrounding Kunming main city were got. The results indicated: 1)the theoretical and actual monitoring coverage rates of forest fires in forest mountain surrounding Kunming main city before the participation of urban grid supervisors were 93.2% and 43.83%, respectively. 2)The area of forest fire monitoring in forest mountain surrounding Kunming main city of urban grid supervisors was 123.92 km~2, with a coverage rate of 45.24%. 3)After the participation of urban grid supervisors, the coverage rate of forest fire monitoring in forest mountain surrounding Kunming main city was 63.23%, which was 20.4% higher than now. The participation of urban grid supervisors can improve the coverage rate of forest fire monitoring in forest mountain surrounding Kunming main city. It is suggested that in the future forest fire monitoring work, the visual radius and field coverage of video surveillance should be comprehensively considered in order to allocate monitoring resources more scientifically. At the same time, with the participation of Urban Grid Supervisors, joint forest fire prevention and control should be carried out to improve forest fire monitoring coverage.