Abstract: Pumped storage power stations (PSPSs) play a vital role in enhancing the power system stability. Common types of the PSPS include hybrid and conventional PSPSs. However, the substitution ratio between their installed capacities remains unclear under equivalent improvements in power system efficiency. This study considers both hybrid and conventional PSPSs, and develops scheduling models for hydro–thermal–wind–solar–storage multi-energy complementary systems to evaluate indicators, including the total stored energy in cascade hydropower stations and power supply reliability. Using the Geheyan-Gaobazhou cascade hydropower stations as a case study, the results show that, compared with conventional PSPS, incorporating hybrid PSPS increases the total stored energy in cascade hydropower stations at the end of the scheduling period by 47.91% and improves power supply reliability by 2.87%. Furthermore, when the unserved energy amounts to 10 million kWh, a hybrid PSPS requires only 0.76 times the installed capacity of a conventional PSPS to achieve higher power supply reliability while enhancing the total stored energy in cascade hydropower stations. This study provides scientific support for the installed capacity selection of PSPS.