The invention discloses a parallel shaft speed adjustment device of a feeder in order to solve the problem that in the prior art, the rotating speed of parallel driving shafts which rotate simultaneously needs to be adjusted in an automatic inverse ratio mode. The parallel shaft speed adjustment device comprises a machine frame, a first driving shaft and a second driving shaft and further comprise a rocker, wherein the first driving shaft and the second driving shaft are connected to the machine frame in a rotatable mode, and the rocker is hinged to the machine frame and located between the first driving shaft and the second driving shaft. A rotating shaft is arranged in the middle section of the rocker, the rotating shaft is connected with two convex disks with opposite convex faces in a rotatable mode, the convex faces are conical, a spring for driving the two convex disks to butt against each other is arranged on the rotating shaft, the first driving shaft is connected with a first driven disk, the second driving shaft is connected with a second driven disk, the edge of the first driven disk and the edge of the second driven disk are both arranged between the gap formed by clamping the two convex disks, and the part, located between a hinged point of the machine frame and the rotating shaft, of the rocker is a telescopic rod with adjustable length. On the basis of the structure, the rotation speed of the first driving shaft and the rotation speed of the second driving shaft are adjustable and are in inverse ratio.