Abstract: In order to define the best turbidimetry condition and key factor between SO2-4 and Ba2+,orthogonal test was applied to investigate the effect of the acidity,the value of buffer solution,the weight of BaCl2,the agitation time and the standing time on the result of turbidimetry.The best experimental conditions were selected by square error analysis.The method was used to total sulfer determination in plant.The recoveries of the method were in a range of 96.8%～104.5%.The method was also applied to the determination of sulfer in standard reference sample (GBW08315) with satisfactory result.