Abstract: The large-scale development of renewable energy power in China is faced with the challenges of the reverse regional distribution of wind and solar resources and power load, and intermittency and randomness of renewable energy power. In this regard, some scholar has proposed the concept of "supply-side base integrated energy system", which proposes to promote the utilization of wind and solar resources through multi-energy cooperation, ultra-high voltage (UHV) direct current (DC) transmission and local consumption. Based on the concept, this paper carried out modeling and optimization research on the real case of Northwest China to further clarify the system scheme and optimization principles. First, the design criteria and technical options were proposed through policy review and engineering project investigation. Then, with the objective function of maximizing the proportion of wind and solar power and minimizing the total cost, 2 types of system optimization model, including the supply-side base integrated energy systems considering only UHV DC transmission and further considering local demand response, were built. The Pareto optimal fronts were obtained, and the evolution pattern of system was analyzed with the continuous improvement of wind and solar power's proportion. The study finds that, in order to realize the high proportion of wind and solar power in cross-regional transmission, more attention should be paid to the construction of wind turbines, natural gas combine cycle (NGCC) and lithium battery (LiB) energy storage units to form such integrated bases. In addition, demand response mechanism should be introduced as soon as possible to improve the economy of cross-regional power transmission and also increase local consumption of renewable energy.