The invention discloses a transmission device of a tool bit angle-adjustable electric screwdriver. The transmission device comprises a cylindrical column, an universal shaft, a driven shaft and a driving shaft; a chute is formed in the side surface of the driving shaft, and is parallel to the axis of the driving shaft; the chute penetrates from the middle part of the driving shaft to a free end of the driving shaft; a slide plate is mounted in the chute, and is mounted at one end of the driven shaft; a turntable is fixedly mounted on the driven shaft; the driven shaft vertically penetrates through the middle part of the turntable; a circular groove is formed in the turntable; a second ball body is mounted in the circular groove, and is connected with a piston rod; the piston rod is connected with a hydraulic cylinder; the other end of the driven shaft is connected with a rotating shaft through an universal shaft; a first ball body is fixedly mounted on the rotating shaft; the axis of the rotating shaft penetrates through the ball center of the first ball body; and the first ball body is mounted in the cylindrical column. The transmission device is adjustable in tool bit angle of the electric screwdriver, can enable the electric screwdriver to work under abnormal working conditions, and is convenient and practical.