Oven gas generated from coking mainly contains CH4, CO, H2, CO2, hydrocarbon etc. and NH3, tar, naphthalene, benzene and other chemicals. Tar, benzene and ammonia are separated from crude gas by condensation. With further disposed, the gas can be used as town gas, fuel for power generation and raw materials for hydrogen production when toxic ingredients of naphthalene, benzene,sulphide and cyanide etc.. This technology usually is applied in metallurgy, steel and coking industry.