Abstract: Hysteresis curves are widely used in the seismic performance assessment of structural systems and members. In the literature on earthquake engineering, most experimental studies involved the analysis of hysteresis curves. Although the research background and objectives may differ, these studies somehow adopted the same methods in analyzing the hysteresis curves. This paper reviews the primary seismic performance indexes based on hysteresis curves, on their definition, on calculation methods, and on limitations. Then, we endeavored to clarify the vague definitions and optimized the calculation algorithms of these indexes. In particular, we proposed a concave hull method for extracting skeleton curves, a directed energy dissipation method, a modified farthest point method, and a method for evaluating the similarity of hysteresis curve shapes. An automatic program for analyzing hysteresis curves is implemented in MATLAB and, validated against the literature's hysteresis curve data. The results illustrated the improved clarity and wide applicability of the indexes proposed and, justified the efficiency and accuracy of the algorithms proposed for identifying these indexes.