Deepening the supply side structural reform of museums in China refers to resolving the structural problems in the cultural supply of museums through reform, enhancing the adaptability of supply structure to demand, improving the cultural supply level and production efficiency, as well as balancing the relationship between supply and demand; it is the embodiment of China’s economic “new normal” in the development of museums. This paper discusses the necessity of the supply side reform of museums in China, the existing structural problems, and the concept as well as main contents of effective supply.