Aeroengine oil contains wear debris generated by friction. Based on the Dempster-Shafer evidence combination theory, aeroengine wear conditions can be effectively diagnosed. Through analysising the elements of wear debris in lubricating meduim, it can determine engines wear levels and wear parts, as references for troubleshooting. In the process of combination, an method was proposed that every element of wear quantity and wear rate were fused at first,then the integration of all elements. For Dempster-Shafer has its own limitations, two impoved methods were applied to and were compared. The results show that Dempster-Shafer evidence combination is an effective fault diagnosis method for aeroengine oil wear condition.