Abstract: A simplified model of temperature and thermal stress fields is solved and verified in this study using steady-state analysis to understand the impact of temperature load in the outlet section of dam galleries on arch dam working behavior under changing environment. In sensibility analysis, we distinguish unfavorable working conditions by different seasons, and find out reasonable measures separately for the conditions of each type according to the uniform design criterion to improve the working behavior. Typical impacts of temperature load are demonstrated through a case study of a super-high arch dam in Southwest China. Results show that the temperature load of this type has a significant impact on dam working behavior and shifts markedly the distribution of temperature and thermal stress in the dam. The working behavior of arch dams can be improved by controlling two sensitivity factors: airflow velocity in the gallery and equivalent heat emission coefficient of the gallery isolating layer.