Accelerating the planning and construction of large-scale wind and solar power bases in Gobi Desert regions is a significant measure for China to achieve its "carbon neutral" targets. The transmission of power from large renewable energy power generation base is highly volatile and stochastic, necessitating the research of suitable planning methodologies for such bases. Taking into account the uncertainties of wind and photovoltaic output as well as the water-electric coupling effects between cascaded pumped-storage hydropower stations, this study proposes a synergistic planning approach for renewable energy power bases integrated with cascade pumped storage power station. Case studies based on a realistic renewable energy power generation base demonstrate the improvement in planning outcomes achieved by this approach compared to traditional independent hydropower planning, thus validating the effectiveness of the proposed method.