The utility model discloses transmission belt tensioning equipment and a transmission belt driving system. The transmission belt tensioning device comprises a tensioning body, two tensioning wheels and a balance structure. Wherein the balance structure comprises two connecting parts; wherein the balance structure is arranged on the tensioning body; wherein one tensioning wheel is arranged on one connecting part, the other tensioning wheel is arranged on the other connecting part, a balance state is formed, and when one tensioning wheel is driven, the balance structure drives the other tensioning wheel to slide in a delayed mode so that the other balance state can be achieved.