The invention relates to a polar crane with an electric over-rail, which is characterized in that the rail is an annular rail hanged on the top part of a plant, a main beam and a driving motor thereof operating along the rail are movably arranged on the rail, a trolley and a driving motor thereof operating along the main beam are arranged on the main beam, the top part of the plant on the outer side of a plant gate on one side of the annular rail is provided with an outer beam which is arranged on the plane with the main beam and extend outwards, the top part of the plant is also provided with a middle rotating beam connecting the main beam and the outer beam, a rotating mechanism is arranged on the middle rotating beam, and an over-rail device is arranged on the middle rotating beam between the main beam and the outer beam. Therefore, the accurate hoisting can be realized at any point in the circular plant, and the stable and smooth transition can be achieved for the hoisting component from the circular plant to another plant. Moreover, the invention solves the problems of hoisting and hoisting-out of the circular plant. In addition, the invention has the advantages of simple structure, easy manufacture and high safety and reliability.