The aircraft landing light and airport approach light are both providing illumination for civil aircraft during night flight. Both of them are significant for aircraft flight safety. The CCAR121 regulation requires that two landing lights should be installed at least in the aircraft, and the AC-97-FS-2011-01 regulation requires that approach light should be installed on the civil airport. The effect of the landing light and airport approach light during night flight is analyzed, and the relationship between them is discussed.