In　order　to　realize　the　intelligent　navigation　and　obstacle　avoidance　of　unmanned　aerial　vehicles　(UAV),　the　distribution　characteristics　of　spatial　electric　field　intensity　are　studied　in　the　paper.　A　three-dimensional　calculation　model　of　AC　500　kV　vertical　crossing　220　kV　transmission　line　was　established　to　study　the　electric　field　intensity　distribution　in　the　paper　by　using　the　estimation　method　of　three-dimensional　electric　field　and　the　finite　element　analysis　software　(Ansys).　The　results　show　that　the　electric　field　intensity　rises　at　first　and　then　goes　down　with　the　change　of　the　test　point　height　in　the　case　of　keeping　the　horizontal　distance.　The　higher　voltage　level　line　plays　a　leading　role　in　the　crossing　area.　In　addition,　the　electric　field　intensity　is　obviously　decreased　along　with　the　increase　of　the　distance　between　the　test　point　and　the　crossing　area　in　the　case　of　keeping　the　height　of　test　point.　In　this　paper,　a　small　multi　rotor　UAV　equipped　with　test　equipment　is　used　to　measure　the　electric　field　in　the　crossing　area.　The　result　shows　that　the　error　value　is　within　the　allowable　range,　which　proves　the　validity　of　the　analytic　results.　The　research　of　this　paper　provides　reference　value　for　the　analysis　of　space　electromagnetic　field.　©　2017,　Harbin　University　of　Science　and　Technology　Publication.　All　right　reserved.