The invention discloses a device for modularly controlling an ORP reactor, and relates to the field of microbial fermentation and microbial electrosynthesis. The device comprises a ventilation/reagenttransfer system, an electric energy input system, a fermentation system and an ORP regulation system; the ORP regulation system is used for monitoring ORP of the fermentation system and controlling ventilation and reagent and voltage input; a gas output end and a reagent output end of the ventilation/reagent transfer system are connected with a tank cover through transfer pipelines respectively and penetrate through the tank cover to be fixed to the tank cover; the electric energy input system is fixed to the tank cover and connected with the ORP regulation system through a wire; the tank cover is detachable, and the ventilation/reagent transfer system and the electric energy input system can be switched rapidly. Accordingly, three types of devices for controlling the ORP are modularized,thus different control methods can be selected for different fermentation systems, the yield and efficiency of products produced through biological fermentation are promoted, and a new idea is provided for the fermentation industry.