As flashover accidents because of strong wind and storm frequently appear in our country, storms are thought to be one cause of flashover between tower and conducting wires in transmission lines.The influence of rainfall intensity,rainwater resistivity and air temperature on AC discharge characteristic of rod-plane(rod-rod) air gap is mainly investigated.The experimental result shows that,rainfall intensity and rainwater resistivity can reduce AC discharge voltage of rod-plane(rod-rod) air gap,and rainfall intensity has the most obvious effect on AC discharge voltage of rod-plane air gap;when rainfall intensity ranges from 2 to 14 mm/min,AC discharge voltage maximum reduction of 0.4,0.6,0.7 m rod-plane gap is respectively 6.73%,6.54%,6.02%,and maximum reduction of rod-rod gap is respectively 2.66％,3.22%,3.07%;the influence of rainfall intensity on AC discharge voltage of rod-plane is bigger than rod-rod’s;AC discharge voltage of rod-plane air gap increases with the increase of air temperature,and the maximum amplitude is 7.03%.