This study effectively associates the evaluation object tree with attribute nodes by constructing an innovative tree-structured emotion dictionary. Utilizing the TF-IDF algorithm, this paper meticulously classifies the emotional features in opera librettos and adds a list of inspirational word nodes. Further, a basic framework of weighted decision matrix is designed, and the data in the emotion score matrix is normalized by Softmax method, to derive the weight allocation coefficients, according to which the results of weight coefficient allocation of the opera libretto are calculated. In particular, for the adaptation of the famous opera Macbeth, this paper proposes three significant principles to ensure that the emotional Expression of the libretto matches the creative intent. The adapted libretto was subjected to emotion calculation and effect analysis, and the empirical study showed that in the first six minutes of the adaptation, there were two periods characterized by extremely significant emotional tension, in which the emotional tension exceeded 7.5 points in both cases. In the specific dynamic analysis, about 60% of the probability emotional value of clip 2 is located in the first quadrant, which coincides with the expected creative goal. In the correlation analysis of the script adaptation, the correlation between emotional attachment and the audience’s willingness to watch the play is as high as 0.8963, indicating that the adaptation is effective. This study not only innovates the method of emotion analysis of opera libretto in theory, but also provides practical guidance for opera libretto adaptation in practice, which helps to enhance the artistic infectivity of opera works and the audience’s viewing experience.