Based on the analysis of the current research status and field investigation of expansive soil slopes, this paper selected four types of evaluation factors that affect the stability of highway expansive soil slopes: topographical and geological factors, hydrometeorological factors, engineering protection factors, and disturbance factors. There were a total of 16 secondary evaluation indicators, and a multi-level structural index evaluation system was established. On this basis, a fuzzy analytic hierarchy process (Fuzzy-AHP) model for evaluating the stability of highway expansive soil slopes was established, and a case study was conducted to analyze and evaluate the stability of expansive soil slopes on the Shenqiu-Suiping Expressway. The research results indicate that soil swelling, rainfall intensity, and vertical crack depth have the greatest impact on the stability of expansive soil slopes, accounting for 43.8% of the total weight. The stability evaluation level of the expansive soil slope in the VI section of the Shenqiu-Suiping Expressway is level II (relatively stable), which is consistent with the field monitoring situation and verifies the correctness and reliability of the evaluation model.