Abstract: Wind sand flows affect surface electric field and potential on insulators. We established a gas-solid flow model for insulator surrounded by sand and a sand-electricity coupling model made up of high voltage insulator based on finite volume method (FVM). Spatial distribution and deposition of sand on surface of insulator and electric field distribution along insulator under different wind sand flow are calculated. It shows that surface potential and electric field distortion are influenced obviously by wind speed and particle size. Distortion of electric potential increases with increase of wind speed and particle size, while distortion of electric field decreases with increase of wind speed and particle size. Different spatial distribution and deposition of sand make different distortion on potential and electric field along insulator.