An exit warning system and a control method thereof are proposed to prevent a malfunction of a SEA system by distinguishing a person approaching a host vehicle from another vehicle, where the warning system includes a target detection sensor configured to detect a target approaching a host vehicle, and a controller configured to control not to transmit a warning signal of a safety exit assist system, in response to a speed of the target is less than or equal to a threshold speed and a position of the target is positioned within a distance from a vehicle door of the host vehicle.