Abstract: In order to scientifically evaluate the effectiveness of building Happy Rivers and Lakes in mountainous rivers of the Northwest Region, this paper, considering the characteristics of water scarcity, ecological fragility, and significant flood control pressure in the region, selects 16 evaluation indicators from four aspects: safety and stability effectiveness, ecological effectiveness, social effectiveness, and management effectiveness. It constructs an indicator system suitable for evaluating the effectiveness of Happy Rivers and Lakes construction in mountainous rivers of the Northwest Region, establishes an evaluation model using the Fuzzy Analytic Hierarchy Process (FAHP), and conducts an empirical analysis using the Jinling River in Shaanxi Province as a case study. By calculating the weights of each indicator and the comprehensive scores, the governance effectiveness is evaluated, and improvement suggestions are proposed. The results show that this evaluation system is scientific, reasonable, and practical, providing a scientific basis and practical reference for the construction and assessment of regional Happy Rivers and Lakes.