An LED-based optical system and a method of compensating for aging thereof are provided. The LED-based optical system includes LED blocks composed of a predetermined number of LEDs; a sensor which senses output values of the respective LED blocks; and a control block which generates compensation rates by comparing initial output values of the respective LED blocks in an initial state with comparison output values of the LED blocks sensed by the sensor at a comparison time point, and controls current being supplied to the respective LED blocks in accordance with the compensation rates.