The invention discloses a gearing ground engaging wheel structure, a line patrol robot mechanical structure and an obstacle surmounting method therefor and belongs to the technical field of robots. The line patrol robot mechanical structure comprises a rack, the gearing ground engaging wheel structure is mounted on the rack which comprises at least one walking unit, the walking unit comprises at least one pair of partitioning wheels, a first walking wheel arm and a second walking wheel arm are respectively arranged below a driving partitioning wheel and a driven partitioning wheel, and a built-in electric sucking disc and a built-in iron block that are used for controlling butt joining and separating of the partitioning wheels are respectively arranged on the outer sides of the driving partitioning wheel and the driven partitioning wheel. Compared with technologies of the prior art, the gearing ground engaging wheel structure, the line patrol robot mechanical structure and the obstacle surmounting method therefor are advantaged by reduction of labor intensity, reduction of operation cost and capability of obstacle surmounting.