The present invention discloses a horizontal-deflection prevention mechanism for an HVDC relay, comprising a moving contact assembly which comprises a moving reed and moving contacts arranged at left and right ends of the moving reed; an upper section of a pushrod is located above a yoke plate and fixed with the moving reed; a positioning plate is provided on the yoke plate; and a left return spring is connected between a left end of the moving reed and the positioning plate, and a right return spring is connected between a right end of the moving reed and the positioning plate. In the present invention, by the arrangement of a left return spring and a right return spring at the left and right ends of the moving reed at which moving contacts are provided, on one hand, a breaking force can be provided, which allows the moving contacts to quickly separate from the stationary contacts when the moving contacts and the stationary contacts are to be separated from each other, so that the relay makes a response quickly. On the other hand, the left return spring and the right return spring always provide an acting force which prevents the moving reed from rotating horizontally, so as to ensure that the moving contacts and the stationary contacts can come into contact precisely and to thus prevent the occurrence of faults due to the contact between the moving reed and other components.