The invention discloses a single-axis yaw electric bolt tightening machine, which comprises a base, a bracket, a revolving servo motor, an encoder, an output revolving shaft, a small belt wheel, a cog belt, a large belt wheel, a revolving shaft, a swiveling jib, a shaft sleeve, a guide post, a housing plate bracket, an electric tightening shaft assembly, a sleeve, a counterforce support plate, a special sleeve, a counterforce sleeve, a servo motor, a torque sensor, an angle sensor and a connecting shaft, wherein the bracket is fixed on the base, and is provided with the revolving servo motor and the encoder; the revolving servo motor is connected with the output revolving shaft; the output revolving shaft is provided with the small belt wheel; the small belt wheel is matched with the large belt wheel through the cog belt; the large belt wheel is connected with the revolving shaft; the guide post is connected with the swiveling jib through the shaft sleeve, and is fixed on the housing plate bracket; and the electric tightening shaft assembly is fixed in the housing plate bracket.