Each country and the international community as a whole are actively promoting the development of renewable energy with a view to addressing climate change, environmental pollution, and sustainable energy development. For this purpose, most countries have enacted relevant incentives to attract investment from multinational corporations. However, with changes to renewable energy support policies, some legal disputes have also arisen. In addition to international trade disputes, the number of investor-state disputes involving renewable energy has also increased substantially. Among them, Spain, as a typical example, has 35 cases in investor-state arbitration. Currently, China has become the world's largest energy consumer. With the advancement of the Belt and Road Initiative, China’s outward investments will increase dramatically in overseas renewable energy fields. At the same time, as China’s energy sector opens wider to the outside world, more and more foreign capital will be available in renewable energy. The legal system on renewable energy in China is not enough to regulate the new situation of the development of renewable energy. Based on examining the evolution of Spanish laws and policies on renewable energy and the awards of the arbitral tribunals, this article explores how to reform and improve China’s renewable energy legal system and to protect Chinese overseas investors in renewable energy field, and it also provides a reference for evaluation of whether to join the Energy Charter Treaty.