In the process of Original Position Statistic Distribution Analysis, many abnormal higher spark signals exist. They are believed as inclusion signals. Analyzing the time sequence and position of the abnormal spark, It is found that the higher spark signals for S and Mn will appear simultaneously . The reason is that MnS inclusion caused the element concentration enrichment at these zone. Mixing some pure MnS crystal in pure iron powder and pressed by Heat Isostatic Pressing technology, reference samples of MnS inclusion were made . Criteria of abnormal higher spark signals for Mn and S is the measured value from the “blank sample ”.After analyzing the spark behavior of these reference samples using OPA instrument, we can calculate the MnS inclusion concentration through such method. steel samples were analyzed and results is satisfactory.