Exhaust gas post processing system and control method thereof

An exhaust gas post processing method, may include detecting driving conditions of an engine, determining a ratio of soluble organic matter and carbon particles trapped in a diesel particulate filter according to the detected driving conditions, selecting a first predetermined temperature and a first maintain time for eliminating the soluble organic matter according to the ratio of the soluble organic matter and the carbon particles, and controlling a temperature of the diesel particulate filter according thereto, and eliminating the soluble organic matter by sustaining the first predetermined temperature for the first maintain time, selecting a second predetermined temperature for eliminating the carbon particles, and controlling a temperature of the diesel particulate filter according thereto.