China and the US are pursuing carbon neutrality targets as the world's largest emitters. Powered by renewable energy, green electricity is a crucial step to help both countries to realize their carbon neutrality goal. Having similar natural situations and abundant solar and wind resources, both countries' western regions shared significant similarities in the weight of land size, population, and social economy to the nation, which makes both western regions comparable. However, both countries are currently at different developing paces in developing solar and wind energy, which requires an unbiased method to conduct this assessment. This study designed a renewable energy assessment framework by defining vital influential factors and their sub- factors first, then aggregating all normalized values of selected factors to conduct a final performance score for each province and state in both western regions. Additionally, a ranking can be given within each region based on the final normalized score. Overall, the results show that although the two western regions are in different development stages, both share similarities in their solar and wind performance except the performance on social policy, as the western US has more types of solar, and consumers can choose incentives. At the provincial and state level, the top three performers in western China and the western US are Inner Mongolia, Qinghai, Ningxia, Colorado, Arizona, and Wyoming, respectively. Based on the performance result, recommended policy implications are given to both western regions for future usage. This framework can be applied to other renewable energy development assessments after successfully defining the key factors and their sub-factors.