The closing law of guide vane in hydropower station affects the resulting hydraulic transients, which should have good robust performance. A comprehensive evaluation method for the robustness of guide vane closing law is constructed by using a penalty function and a weight function to generate the evaluation indexes of the hydraulic turbine's large fluctuation transition process from maximum rise rate of spiral case pressure, maximum draft tube vacuum, and maximum rise rate of rotational speed. The effect of various inflection point times, inflection point opening degrees, and guide vane effective closing times for a moderately-high head hydropower station on these three regulating guarantee parameters were evaluated by the orthogonal experimental method. The results show that the effective closing time has a relatively small influence on these three regulating guarantee parameters, while the inflection point opening degree and the inflection point time significantly affect the balance between the water hammer pressure and the unit's speed. These evaluation results for the guide vane closing process not only lead to each regulating guarantee parameter having sufficient safety margin, but also to a robust control system. This robustness evaluation method provides a reference for reasonable selection of guide vane closing law of moderately-high head hydropower plants.