This article introduces the sources and utility circumstances of tail gas (off-gas, C3, C4, and C5 sources) in China. The utility circumstances of off-gas, C3, C4, and C5 sources are discussed in detail. Furthermore, the flow charts of C4 and C5 utilization in a chemical plant are shown. According to the full utility of off-gas, C3, C4, and C5 sources, their good economic and social benefits are obtained.