The present invention provides an optical disc drive system and a method for performing servo defect compensating operation. A method for performing a servo defect compensating operation by compensating a servo-related signal in an optical disc drive and a related optical disc drive system with a DSP is provided. The method comprises: reading an optical medium by an optical pick-up unit; detecting whether a defect exists by monitoring a side beam signal; when the defect on the optical medium is detected, determining a new compensation value based on a servo error signal; and compensating the servo-related signal with the new compensation value during defect crossing to adjust servo control when the optical pick-up unit passes the defect.