A two-fold four-wheel golf bag cart folding device includes a lower cart frame having a connecting plate installed at an upper end of the lower cart frame and a lower supporting base disposed at a lower end of the lower cart frame. An upper cart frame includes a lower end coupled to the connecting plate and has an upper supporting base and a handle module at an upper end, such that the upper supporting base and the lower supporting base are fixed to the golf bag. A rear wheel stand is mounted on both sides of the connecting plate and has a rear wheel. A pull rod includes an end coupled to the handle module and the other end coupled to the rear wheel stand. A front wheel set has two front wheels installed on both sides of the lower supporting base respectively. A locking mechanism is installed between an upper end of the upper cart frame and a lower end of the handle module and has a function of fixing an angle between the upper cart frame and the handle module. A four-link-rod mechanism is installed among the handle module, the rear wheel stand and the pull rod. The front wheels can be closed synchronously while the rear wheels are being folded, and the four wheels touch the ground simultaneously to skip the step of folding the front wheels and removing the golf bag, preventing staining the user, but also facilitating the user to carry and move the golf bag cart and to store both the golf bag and cart altogether.