Abstract: Transformer maintenance strategy decision is a decision-making problem of hybrid multiple attribute index related to coexistence of quantitative indicators and qualitative indexes. The fuzzy comprehensive evaluation analysis model of the transformer maintenance strategy was set up by using fuzzy TOPSIS， and the decision-making problem of hybrid multiple attribute index was solved. Through calculating the relative closeness degree to determine the transformers operation status， the transformer maintenance strategy could be determined by using the proposed method. In addition， the proposed method not only can monitor transformers operation status，but also can directly determine the best one from various maintenance strategy for a transformer using the expert system . The index values of accurate real type， interval type and fuzzy number were classed and judged， then the relative closeness degree of various maintenance strategy was sorted through analysis and comparison， based on which it could be decided to choose which kind of maintenance strategy. The result of the example shows that the method has good effect on transformer maintenance strategy decision.

Key words: power transformer, fuzzy TOPSIS, hybrid multiple attribute decision making, maintenance strategy, decision-making