The accuracy and fairness of the assessment results to a large extent limited by the choice of methods of assessment data processing. In the current practice of the equipment support core competencies (ESCC) assessment, there are two methods of assessment data processing mainly used, which are named the simple arithmetic average method and the weighted arithmetic average method. In this paper, an assessment data processing method is given, which is based on the accuracy of the expert assessment data. This method can be better to eliminate the subjectivity and contingency of expert assessment, and to improve the fairness and reliability of the assessment results.