In northern China, there is a serious problem of source-load imbalance and significant wind curtailment, mainly due to the limitations of the “heat determines electricity” mode of operation of combined heat and power (CHP) units in winter. To further absorb excess wind power and overcome these limitations, this paper proposes an optimized scheduling method for a regional integrated energy system (RIES) based on source-load coordination. Firstly, on the supply side, the paper introduces the concept of a concentrated solar power (CSP) plant and an electric boiler for combined heat and power generation to provide heating, partially decoupling their operation mode from “heat determines electricity.” Secondly, on the demand side, the impact of electric vehicles (EV) is considered. A formula for the fluctuation ratio of peak-to-off-peak electricity prices is established, and EV charging and discharging are guided by electricity prices to fully exploit the demand response capability of dispatchable resources on the demand side. Charging loads during peak electricity consumption periods are effectively shifted to off-peak periods, aiding in peak shaving and valley filling. Finally, a tiered carbon trading mechanism is introduced. With the goal of minimizing the total cost of the RIES, an optimization scheduling model for the RIES is established, and the CPLEX solver is used for solving. Simulation results show that under source-load coordination scheduling, the overall efficiency of the system is significantly improved. It can further overcome the limitations of CHP units, enhance wind power consumption capacity, reduce carbon emissions, and improve the economic benefits of the RIES.