An oil return mechanism includes a base, a control switch, a first blocking ball mounted in the base, an elastic member mounted between the first blocking ball and the base. The base has a liquid storing cavity, a liquid returning cavity, a communicating cavity, a first communicating opening communicating between the liquid returning cavity and the communicating cavity, and a second communicating opening communicating between the communicating cavity and the liquid storing cavity. The present invention can regulate a speed of a fluid flowing from the liquid returning cavity to the communicating cavity, and has the advantages of simple structure and great reduction of cost.