The invention discloses a CO2 electroreduction electrolysis tank. A solution flow field plate in the electrolysis tank is provided with flow channels penetrating through a first insulating surface anda second insulating surface, and the flow channels cooperate with a cathode gas diffusion electrode and an electrolyte supporting layer to form an electrolyte cavity for a reaction of CO2 with an electrolyte. The first insulating surface of the solution flow field plate is provided with a groove, and the electrolyte supporting layer is embedded in the groove to make the solution flow field platein close fit with the electrolyte supporting layer. A feeding groove communicated with the electrolyte cavity is arranged at one end of the electrolyte cavity, the feeding groove is communicated witha material channel, a discharge groove communicated with the electrolyte cavity is arranged at the opposite end of the electrolyte cavity, and the discharge groove is communicated with the material channel. The flow channels increase the flow paths of reactants in the electrolyte cavity, so the reaction degree of the reactants is increased, and the attenuation rate of the CO2 electrical reductionability is reduced, thereby the stability of the CO2 electrical reduction ability in the long-time reaction process is increased, and the stability of the product yield is ensured.