An automatic filter press of diaphragm malt extract and its process for saccharifying wort and filtering beer are disclosed. The process is carried out by shutting up malt filter press, retaining pressure automatically, charging stocks, filling wort into filter press by down-wort pump fast, pumping wort into from feed opening at one side of filter-pressing board bottom, filter pressing, filling filter press with wort, running malt extract out of liquid outlet at another side, flowing into boiler through balancing tank, inspecting non-material by mashing tub, shutting up down-wort pump automatically, filtering malt extract, blowing while extruding tank layer by diaphragm, press drying for tank layer, washing tank, pumping tank-washing water by down-wort pump, passing through tank layer and running out, reaching tank-washing water to a certain account, shutting up down-wort pump automatically, re-blowing while extruding tank layer from diaphragm, press drying for tank layer, opening exhaust valve of pipeline, discharging compression air in diaphragm board, opening filter board and dropping malt wort into bucket automatically.