Under the ambitious commitment of reaching carbon neutrality by 2060, China promotes both the deployment of renewable energy and the development of electric vehicles. Renewable fluctuations in the supply side and EV charging burden in the demand side propose higher requirements for the system flexibility. Optimized station layout and charging schedule could coordinate the load curve, provide system flexibility and accommodate the variable renewables. However, previous work only focuses on maximizing the profit of station holders and vehicle owners, lacking the consideration of the broader impact on power system. Here, we propose an EV charging station layout optimization methodology considering not only the EV charging behavior, sequential charging demand, but also its further impact on power system. The station layout and charging schedule are co-optimized with an integrated power system model. Applying the proposed methodology to Jiangxi in 2025, a cumulative charging station capacity of 1412, 1092, and 1415 MW is recommended in workplaces, residences, and shopping centers, respectively. Increased renewable energy integration and decreased thermal power generation are realized, achieving reduced carbon emissions of 800 kilotons. This work provides an effective methodology for slow charging station layout from the perspective of the integrated power system.