Building-Integrated Photovoltaics (BIPV) offer a promising solution to enhance building energy efficiency and reduce building energy consumption. Among the various application of BIPV, BIPV windows stand out as an intriguing and notable example. This paper investigates an office building with BIPV windows in five different climatic cities in China. The study considers four variables, including building orientation (BO), window size (WZ), window visible light transmittance (VLT), and type of PV (TOPV). The objective is to minimize both the annual net electricity cost (ANEC) and the extra investment cost of BIPV windows. To simulate the design variables and objective functions, the jEPlus software is employed. Additionally, the jEPlus + EA software uses the SRC and Morris algorithms for sensitivity analysis of design parameters. The multi-objective problem is addressed using the NSGA-II. By conducting optimization, a set of Pareto optimal solutions were obtained. The results demonstrate that the building with BIPV windows can save a minimum of 6.83 % annual electricity costs. Moreover, the static investment payback period for all cities ranges from 7 to 14 years, indicating the economic feasibility of implementing BIPV windows.