The invention belongs to the technical field of bioreactors, and particularly relates to a tower reactor capable of well increasing the gas-liquid mass transfer coefficient in the anaerobic fermentation process of synthesis gas. The reactor comprises a fermentation tank, a tower plate system, a synthesis gas control system and a fermentation liquor circulation system, wherein the tower plate system is arranged in the fermentation tank, and the synthesis gas control system and the fermentation liquor circulation system are both connected with the fermentation tank. Through the fermentation liquor circulation system, microorganisms can obtain a uniform growing environment; through the tower plate system, a recombinant contact space is provided for contact between the microorganisms and the synthesis gas, and the utilization rate of the synthesis gas can be better increased; through the synthesis gas control system, the charge amount of the synthesis gas can be accurately controlled, the reaction rate can be adjusted, and then resource waste can be avoided. The tower reactor has the advantages of being high in adjustability, wide in application range, high in gas-liquid mass transfer coefficient, good in synthesis gas conversion rate and the like and has good application and popularization prospects in biomass conversion and synthesis utilization.