A line fixing device of a transformer for weak current engineer includes struts, the struts and the left and right sides of the upper end of the lower transformer are in threaded connection through screw holes, a set of mounting blocks are fixedly connected with the lower parts of both sides of each strut, a set of deflectors are fixedly connected to the outside of the mounting block, thread holesare arranged at the central position on both sides of the strut, a rotary handle is fixedly connected with the top end of the strut, the left and right sides of the rotary handle are each provided with a set of fixing rings, and the fixing ring comprises a first limiting plate, a second limiting plate, connecting pipes and a connecting rod, wherein the first limiting plate and the second limitingplate are connected through the sleeve joint of the connecting pipes and a moveable rode, and a connecting rod is arranged on the left sides of the first limiting plate and the second limiting plate.According to the invention, the fixing rings, the air guide plate, the deflectors, the arranged thread holes, the screw holes and the mounting blocks are arranged, the line fixing device has the advantages of convenient installation and disassembly, convenient use and capability of fixing lines with different sizes.