A method of auto-retracting a lens of an image capture apparatus and a control system using the same are applied to an image capture apparatus with a retractable lens. The method includes the following steps. A hardware circuit of the image capture apparatus detects whether an abnormal power failure event occurs or not. The hardware circuit performs a re-boot procedure when detects that the abnormal power failure event occurs. After the hardware circuit performs the re-boot procedure, software in the image capture apparatus utilizes residual power only to perform a control procedure of retracting the lens. After the retractable lens is detected to have been retracted into the image capture apparatus, the software controls the image capture apparatus to be powered off.