The invention provides a nuclear facility retirement scheme evaluation method and system, and the method comprises the steps: determining indexes and index levels for evaluating a retirement scheme, and constructing a multi-level evaluation index system; calculating the importance of each index under the same upper-layer index and forming a weight row matrix; dividing each index into a plurality of good and bad grades, and specifying to obtain the score of each good and bad grade; calculating the membership degree of each final-stage index belonging to each quality grade to form a membership degree row matrix, forming a membership degree matrix by the membership degree row matrix of each final-stage index under the same upper-layer index, multiplying the membership degree matrix by the weight row matrix to obtain a membership degree row matrix of the upper-layer index, and calculating layer by layer to obtain a membership degree row matrix of the retirement scheme; and multiplying themembership degree row matrix of the retirement scheme by the score of each quality grade to obtain a quantitative score of the retirement scheme. According to the method, a standardized decision process is provided for nuclear facility retirement scheme evaluation, and quantitative evaluation of the nuclear facility retirement scheme is realized, so that deterministic judgment is provided for decision making.