The invention provides a dual power supply transfer switch and a mechanism applied to the dual power supply transfer switch. The dual power supply transfer switch comprises a first power supply terminal (1) and a second power supply terminal (2); the mechanism applied to the dual power supply transfer switch comprises a driving part, a driven part (6) coupled with the driving part, and a two-directional separating limiting part; wherein the driving part is configured to drive the driven part (6), so that a moving contact (7) connected to the driven part (6) rotates counterclockwise or clockwise; and the two-directional separating limiting part is configured to cooperate with the driving part when starting, so that the moving contact (7) is located at a two-directional separating position that is not connected to any one of the first power supply terminal (1) and the second power supply terminal (2).