The invention discloses a parallel shaft self-aligning coupler. The parallel shaft self-aligning coupler comprises a driving plate (2), an intermediate transitional plate (4), a driven plate (6) and a pin (7), wherein the pin (7) is respectively installed in a pin hole of the driving plate (2) and a pin hole of the driven plate (6), the pin (7) is connected with a connecting plate (1), and the intermediate transitional plate (4) is respectively connected with the driving plate (2) and the driven plate (6) through the connecting plate (1) and the pin (7). According to the parallel shaft self-aligning coupler, the intermediate transitional plate is additionally arranged between the driving plate and the driven plate and respectively connected with the driving plate and the driven plate through the pin and the connecting plate, so that the torque can be transmitted in the self-aligning movement, and the power transmission problem when a driving rotating member is not concentric with a driven rotating member can be solved.