The invention provides a windproof device of a natural ventilation dry type air cooling tower. The windproof device is characterized in that air cooling radiators are arranged around the lower end of the air cooling tower; the natural ventilation dry type air cooling tower comprises fin walls which are vertically arranged outside the air cooling radiators; the two fin walls are symmetrically arranged in the radial direction of the air cooling tower; the widths of the fin walls are greater than or equal to the heights of the fin walls; and a plurality of through holes are formed in the fin walls. According to the windproof device, the wide fin walls are arranged outside the air cooling tower, and the wide fin walls are perpendicular to environmental cross wind and can effectively change the pressure distribution outside the radiators, weaken the adverse effect of the environmental cross wind on the air cooling tower and improve the economic benefit of a power plant.