This article introduces the source and utility circumstance of C4 source in China. The utility circumstance of C4 is discussed in detail. For example, C4 source is hydrogenated as steam cracking feedstock; it is used as a gasoline oxidizer; C4 source is separated to get 1-butylenes, gasoline, n-butylenes, and tribenzene, respectively; C4 source is used as an antioxidant and fuel. Furthermore, a flow chart of C4 utilization in a chemical plant is provided. According to the full utility of a C4 source, good economic and social benefits are obtained.