In recent years, two moderate earthquakes of magnitude 6.0 occurred near the Huayingshan fault zone, a critical boundary fault within the Sichuan Basin. Therefore, it is crucial to study the activity characteristics of the Huayingshan fault. From the sedimentary history analysis of the study area, river terraces were first extracted using medium-resolution digital elevation models (DEMs). These terraces were then validated using high-resolution DEM from unmanned aerial vehicles and field surveys. Finally, the spatial distribution characteristics of terraces along the Minjiang River, Jinsha River, Yangtze River, and Tuojiang River in the southwest segment of the Huayingshan fault were systematically obtained. On the basis of the deformation characteristics and formation ages of the stratified geomorphic surfaces, the southwest segment of the Huayingshan fault exhibited significant activity during the Middle Pleistocene but weakened or ceased activity in the Late Pleistocene. These findings provide critical insights for seismic hazard assessment of the southwest segment of the Huayingshan fault and the identification of seismogenic structures of recent moderate earthquakes.