Iconic symbols in the digital age, as an important part of app design, play a central role in transmitting information between the app and the visitor. To optimize the design of mental health app navigation bar icons and improve the user experience of mental health apps. The design features are summarized by analyzing the current design status of existing mental health app navigation bar icons; the hierarchical analysis method is used to determine the evaluation index system of the navigation bar icon of the mental health app, the fuzzy judgment matrix is determined through the expert survey and the SPSS software is used to calculate the weight value of each evaluation element; redesigning mental health app navigation bar icons by refining design elements through icon recognition experiments and user preference surveys; evaluation and analysis of the program using fuzzy comprehensive evaluation to demonstrate the feasibility of this design solution. The evaluation results show that the scheme achieves the effective integration of recognizability, interactivity and aesthetics. In conclusion, a method for designing and evaluating the navigation bar icon of mental health apps based on fuzzy hierarchical analysis is proposed, and the feasibility of the method is verified through a specific design scheme.