A dual stage gas generator, also known as a two-stage gas generator, has two gas outlets, upper and lower, which can output gas with different calorific values. Its gasification efficiency and comprehensive thermal efficiency are higher than those of a single stage furnace. The coal is thoroughly distilled in the upper section of the furnace, and the lower section of the gas basically does not contain tar. The upper section of the coal gas contains a small amount of light tar, which is not easy to block the pipeline. The two-stage furnace gas has a high and stable calorific value, high operating flexibility, and high degree of automation, Low labor intensity. The two-stage furnace gas station does not pollute the environment, saves water significantly, occupies a small area, and has low long-term operating costs.