Precise measurement of O4 slant column density(SCD) is meaningful for aerosol profile retrieval. Error correcting methods of O4 SCD measured with multi axis differential optical absorption spectroscopy(MAX-DOAS) is presented. Correcting factor is calculated by comparing O4 SCD measurement result of 30° and simulation result through radiative transfer model(RTM). This factor is used to correct SCDs of each elevation angle, to remove the retrieval error caused by O4 cross section absolute error and improve the SCDs precision. The result is applied to O4 SCD measurement at Hefei, and provides a possibility for aerosol profile retrieval of next step.