The invention belongs to the technical field of biomass gasifiers and relates to a flat bottom ash discharging hopper and open ash discharging auger system. The flat bottom ash discharging hopper and open ash discharging auger system comprises a flat bottom ash discharging hopper; annular water is arranged at an outer ring of the flat bottom ash discharging hopper; a convex water jacket is arranged at the middle inside the flat bottom ash discharging hopper; an ash pan base plate is rotationally arranged at the top of the convex water jacket; a plurality of ash scrapers are uniformly arranged at the bottom of the outer ring of the ash pan base plate; an open slot in the bottom of the flat bottom ash discharging hopper is connected with an ash inlet of an open ash discharging auger. According to the system disclosed by the invention, dry ash can be discharged, and the ash can be cooled and is prevented from being blocked; the flat bottom ash discharging hopper and open ash discharging auger system is reliable in operation and uniform and adjustable in ash discharge; the height of equipment is reduced.