The invention relates to the technical field of energy, and discloses a flue gas emission system and a combustion gas turbine. The flue gas emission system comprises a heat regenerator, a first pipeline and a flow adjusting assembly. The flow adjusting assembly is used for adjusting flow proportion of flue gas entering the heat regenerator and the first pipeline; an opening in one end of the heatregenerator communicates with a gas outlet of a flue gas generating system of the combustion gas turbine; an opening in the other end of the heat regenerator is connected into the first pipeline; an opening in one end of the first pipeline communicates with an outlet of the flue gas generating system of the combustion gas turbine; an opening in the other end of the first pipeline is used for emitting flue gas; the flow adjusting assembly is adjusted to change the flow proportion of the flue gas entering the heat regenerator and the first pipeline, the temperature of the gathered flue gas can be changed, and the temperature of flue gas discharged by the flue gas emission system is changed arbitrarily between the temperature of flue gas emitted by the gas outlet of the flue gas generating system and the temperature of the flue gas subjected to heat exchange of the heat regenerator, so that the temperature of the flue gas emitted by the flue gas emission system can be adjusted, the structure is simple, and an adjusting method is convenient to implement.