An on-screen calibration system for disc drives and the operating method thereof. The calibration system includes an autocollimator detecting the inclined angle of the stage of a disc drive. A control module is connected to the on-screen display module and a bar code scanner to receive the bar code of the pick-up module and compute a predetermined position data. A monitor displays a moving point according to the inclined angle and a target point according to the predetermined position data through an on-screen display module. The tilt-adjusting mechanism supporting the pick-up module is adjusted to shift the moving point overlapping the target point.