Abstract: Wind and photovoltaic power generation, as mature renewable technologies, have been widely applied in power systems. However, their intermittency and uncertainty severely limit long-term supply reliability. To improve the economic performance of multi-energy power systems during the planning stage and enhance renewable energy accommodation, an optimal capacity configuration model for wind-PV-pumped storage considering construction sequencing and a flexibility retrofit scheme for thermal power units were proposed. First, an optimal capacity configuration model for wind-PV-pumped storage considering construction sequencing and a flexibility retrofit model for thermal power units were established, and the objective function as well as various constraints of the optimization model were formulated. The nonlinear parts were linearized using special ordered set of type 2 (SOS2) and McCormick convex envelope relaxation, transforming the original nonlinear problem into a mixed-integer linear programming problem. Based on historical wind, solar, and load data from a multi- energy power system, typical daily scenarios were generated using density peak clustering. Results verify the rationality of the proposed model and retrofit scheme.