The invention relates to a speed change device with a coaxial connecting rod rolling disc. The speed change device comprises a speed changer shell containing a body. The body comprises the coaxial connecting rod rolling disc, a force-input shaft, a centrifugal piece, a plurality of counterweight assemblies, a plurality of O rings and a plurality of sliding block assemblies. When the speed change device conducts actuation, the force-input shaft serves as a force applying point of the lever principle, the equal sliding block assemblies serve as weight points, and the arm of force is equal to thedistance between the force-input shaft and each equal sliding block assembly; the equal sliding block assemblies are arranged at the tail end of the connecting rod rolling disc, therefore, compared with the prior art, the arm of force is increased, the bearing force of the weight points is improved, the turning force of the speed change device is increased under the same motor force, and accordingly the motor force is saved; and in addition, U-shaped grooves for containing the equal sliding block assemblies are formed in the tail end of the connecting rod rolling disc, so that machining is easy during manufacturing, and the cost can be reduced.