The key points and difficulties in vocal singing are problem identification and clever transition in the voice change area. In this paper, by establishing the hierarchical structure model of the hierarchical analysis method, we compare the degree of importance of elements at different levels and the same level based on the judgment matrix to establish the weight vector and test the consistency of the judgment matrix. At the same time, for the problem that the hierarchical analysis method is not strongly targeted, the fuzzy comprehensive evaluation method is proposed for optimization, and then the fuzzy hierarchical analysis method is used to analyze the sound change phenomenon from the three primary indicators of breathing rhythm, resonance effect and sound representation and the related secondary indicators. The evaluation scores of the breathing rhythm control level were 7.83% and 13.77% lower than those of the professional level and master level, respectively; the evaluation scores of resonance effect were 10.70% and 13.37% lower than those of the professional level and master level, respectively; the evaluation scores of sound representation level were 9.26% and 14.32% lower than those of professional level and master level, respectively. The research based on hierarchical analysis can analyze the phenomenon of voice change in the process of vocal singing from a quantitative perspective, give scientific guidance to the practice of vocal singing, and help the development and prosperity of vocal singing art.