This chapter introduces and examines the philosophy of Xiong Shili 熊十力 (1885-1968). Xiong Shili was one of the best-known Neo-Confucian philosophers in the twentieth century. What distinguished him from his contemporaneous Neo-Confucian thinkers was his focus on the construction of the Neo-Confucian ontology that was greatly inspired by The Book of Changes and synthesized Buddhist and Confucian metaphysical ideas to a considerable degree. His philosophy is an attempt to meet challenges of Western philosophy from the Neo-Confucian perspective in modern times. The most distinctive feature of Xiong’s ontology is to emphasize the inseparability of ti (體 original reality/original substance) and yong (用 function). “Ti and yong are not two” (ti yong bu er 體用不二) is the central proposition of Xiong’s ontology. As a Confucian, Xiong didn’t challenge the Song-Ming Confucian way to justify morality by metaphysics and cosmology, but he provided his moral metaphysics for Confucianism in a modern context with new terminologies and arguments. That might partly explain why Xiong’s works have been so much appreciated by contemporary Neo-Confucians and why Xiong is highly respected as one of founding figures of modern Neo-Confucianism.