Remote fault diagnosis (RFD) is of great importance in improving the flight safety, reducing cost of diagnosis and maintenance and establishing a better environment for aircraft maintenance. During the process of remote fault diagnosis, how to make reasonable task decomposition towards complex diagnosis task and how to make the optimal diagnosis decision on redundant or uncertain decisions are vital research issues. In this paper, we present methodologies to improve the diagnosis efficiency and reliability. First, RFD Task Decomposition of multi-resource is descripted in this paper. Then fault tree based minimal cut set is put forward to decompose the complicate RFD task into some smaller executable subtasks. Finally we present decision-level information fusion approach based on Dempster-Shafer (D-S) evidential theory. The examples analysis are given to demonstrate the effectiveness of our approach.