Abstract: When traditional reservoir operation charts incorporate ecological objectives, fixed ecological flow thresholds are commonly used, which fail to respond to intra-annual hydrological rhythm variations and exacerbate conflicts between water supply and ecological demands. To resolve this issue, this study takes Xiyuan Reservoir as a case study, employs the Lyon method to construct dynamic ecological flow thresholds that are synchronized with the intra-annual dry-wet fluctuations of natural runoff, and embeds them into a reverse-order regulation model. Reservoir operation charts are established under three schemes: without ecological objectives, with fixed ecological base flow, and with dynamic thresholds. The influence of different ecological objective integration approaches on the structural characteristics of the operation charts is systematically analyzed.The study analyzed the impact of different ways of incorporating ecological objectives on the structure of operation charts. The results indicate that adding fixed ecological base flow as a constant causes a rigid shift in the operation curve, unidirectional compression of storage in the normal water supply zone, and decoupling from the inflow process. Dynamic thresholds, as time-varying additions, lead to adaptive fluctuations in the operation curve characterized by "rises during flood periods and declines during dry periods," restoring storage in the normal water supply zone, converting regulation from unidirectional compression to bidirectional adjustment, and achieving nonlinear linkage between the operation curve shape and inflow process. Compared with the fixed ecological base flow scenario, dynamic thresholds effectively alleviate conflicts between water supply and ecology, upgrading operation charts from static rigid constraints to dynamic adaptive regulation, enabling coordinated water supply and ecological scheduling. The results provide quantifiable design references for safe water supply and ecological coordination in small- and medium-sized mountainous river basins.