The invention discloses a pulley mechanism used in an electrical installation process. The pulley mechanism comprises two pulley yokes on which pulleys are mounted; each pulley yoke is connected to a bearing rod; the two bearing rods are connected through a connecting rod; the pulley mechanism is characterized by further comprising a brake device which comprises a brake bracket plate fixed to the two bearing rods or two pulley yoke brackets; a threaded through hole is formed in the brake bracket plate; a screw rod is arranged in the threaded through hole; a friction brake body is connected to one end of the screw rod, and a handle is connected to the other end of the screw rod; the two pulleys are suspended above a power line; the friction brake body is positioned in a gap between the power line and the brake bracket plate. The pulley mechanism is simple in structure and low in cost, and can realize brake at a fixed point; the pulley mechanism can be fixed to one particular point due to up and down extrusion; compared with a traditional hook design, the pulley mechanism provided by the invention is convenient to operate, can realize effective positioning, and avoids a sliding risk.