The utility model discloses a corner pulley wheel mechanism which is arranged on an electric cable rack which is used for erecting an electric cable. The electric cable rack comprises a plurality of bearing plates and a plurality of vertical steel channels, the bearing plates are distributed in a top to bottom manner, each bearing plate is shaped as a rectangle, the steel channels are arranged at corners of the rectangle-shaped bearing plates in a supporting manner, the corner pulley wheel mechanism is arranged between corner parts of two neighboring bearing plates, the corner pulley wheel mechanism comprises a first pulley wheel and a support rack, the support rack is fixed on one of the steel channels or the bearing plates, the first pulley wheel is assembled on the support rack, the axial direction of the first pulley wheel and the length direction of the steel channels are the same, and the electric cable arranged at the corner is enabled to pass along the surface of the first pulley wheel. According to the corner pulley wheel mechanism, the electric cable can be enabled to pass by the surface of the pulley wheel when passing by the corner and does not directly rubs against the steel channels, friction force is reduced to the maximum degree, the outer skin of the electric cable cannot be damaged, no worker needs to be arranged at the corners, manpower is saved, and personal injuries can be prevented.