The invention discloses a recovery system and recovery method for converter gas. The recovery system for the converter gas is composed of an evaporative cooling section flue, a dust collector, a gas enriching device, a medium converter gas storage tank, a N2 pipeline, a valve A, a valve B, a valve C, a valve D, a valve E, a valve F, an induced draft fan, a diffusion tower, a switching station and a converter gas recovery cabinet. The recovery system for the converter gas is installed at the outlet end of an evaporative cooling section flue of an original converter gas recovery system. The technical process comprises the steps that the high-temperature converter gas coming out of the evaporative cooling section flue enters the dust collector and then is guided into the gas enriching device for the gasification reaction, 80% or more of CO2 in the converter gas is converted into CO, the enriched converter gas sequentially enters the switching station and the converter gas recovery cabinet under the suction of the induced draft fan after buffering and pressure stabilizing are conducted on the enriched converter gas through the medium converter gas storage tank, and then recovery of the converter gas is completed. The recovery system and recovery method for the converter gas have the effects that the heat value of gas recovered from per ton of steel can be increased, the amount of converter gas recovered from per ton of steel is improved, waste and atmospheric pollution which are caused by diffusion are avoided, and the steelmaking cost is reduced.