The invention relates to a wind generating set yaw angle measuring device. The wind generating set yaw angle measuring device comprises a shell, the bottom end of the shell is provided with a throughhole, a rotating shaft is arranged in the through hole in a matched manner and is fixedly connected with the through hole, the bottom end of the rotating shaft is movably connected with the top end ofa lighthouse, the top end of the rotating shaft is fixedly provided with a horizontal disc, the disc is located in the shell, a horizontal first screw is movably mounted between the inner walls of the two sides of the shell, the first screw is located in the front of the interior of the shell, a first nut is arranged on the first screw in a matched manner, a horizontal guiding rod is fixedly mounted between the inner walls of the two sides of the shell, the guiding rod and the first screw are located on the horizontal face, the guiding rod is located at the rear of the interior of the shell,and the guiding rod is provided with a guiding sleeve in a matched manner. According to the wind generating set yaw angle measuring device, the angle of a wind generating set can be adjusted accordingto the change of the air flowing direction, even if the wind generating set faces the air flowing direction, the angle formed by two times of adjacent wind direction changes can be observed through an angle ruler, adjustment by a worker is facilitated, and adjustment is convenient.