After studying the common defects and faults of transformers, we design and propose a fast fault diagnosis system for transformer equipment based on CBR(Case-Based Reasoning) and RBR(Rule-Based Reasoning). In the system, test cases are firstly matched with the cases. If there are similar cases, CBR is used to obtain the diagnosis conclusion. If there are no similar cases, the rule reasoning module based on FTA (Fault Tree Analysis) is launched. This module subdivides transformer fault modes into winding, core, bushing, on-load tap changer, cooling system, non-electric protection and other fault modes, and forms rules. Based on this situation, a transformer equipment fault tree is established to serve the rapid diagnosis system. The structural characteristics and fault modes of transformer windings, iron cores, bushings, on-load tap changers, cooling systems, non-electrical protection and other equipment are subdivided. And then, a fast fault diagnosis model and system for transformer equipment are established. Finally, the case study proved that the system can diagnose and analyse the equipment faults based on the comprehensive multi-source data of transformers, and the diagnosis conclusion is reliable and practical, which has provided support for realizing the state maintenance of transformers.