The invention provides an angle adjusting device for warning boards of a power transmission line, relating to the field of power equipment. The angle adjusting device comprises a chassis, wherein a driving plate is arranged on the chassis, a plurality of traveling mechanisms are meshed to the driving plate, the traveling mechanisms move along guide grooves in the chassis, and the warning boards are arranged on the traveling mechanisms. For the angle adjusting device provided by the invention, by virtue of the meshing between the traveling mechanisms and the driving plate, and in match with guide plates, the angle adjustment for the plurality of warning boards on the device is realized. By virtue of the design of screw rods and a connecting ring, the deflection of the warning boards in thevertical direction is realized, and meanwhile, a supporting effect is also achieved.