The invention relates to an electric door-locking system to be applied to at least one electric door body that is movable in a sliding manner, and includes forwardly and reversely rotatable screws disposed side by side along a direction in which the electric door body slides at the side of a door frame; a cam assembly provided at a predetermined position of the screws to perform a locking function and an unlocking function; and a sliding unit provided with a locking roller resiliently biased in a direction toward the cam assembly and engaging with the cam assembly to perform the locking function, one end of the sliding unit being rotatably connected to the screw and the other end of the sliding unit being connected to the electric door body.