Evaluating economic life of power transformers can effectively guarantee the safe operation of grid and improve economic efficiency. Full life-cycle cost theory used as a guide, environmental costs and social responsibility costs taken into consideration, a more comprehensive full life-cycle cost model of the transformer is established. Since evaluation parameters have random and fuzzy uncertainty, random fuzzy theory processing evaluation parameters are introduced to handle the two kinds of uncertainty simultaneously and a new assessment of the economic life of the transformer model is established. This model not only can get economic life expectancy of the transformers, but also can get the economic life interval under different confidence levels and interval whose chance measurement is the biggest under the same economic life span. An example result shows that the random and fuzzy theory applied to the transformer economic life assessment is feasible and effective, and it can provide more detailed and diversified information for decision makers and has a certain reference value.