NOVELTY - Increasing the stability of alcohol production includes mixing crushed starch raw materials with last batch of anaerobic outflow water, which is removed with ammonia; adding liquefying enzyme for starch liquefaction; adding saccharifying enzyme for saccharification; fermentation using liquid yeast or active dry yeast; distilling to obtain alcohol; removing sulfate; adding alcohol distilled waste liquid into anaerobic reactor for methane fermentation; and adding alkali into anaerobic outflow water obtained via anaerobic methane fermentation, regulating pH, and removing ammonia.    USE - Increasing the stability of alcohol production (claimed).    ADVANTAGE - The method reduces the content of hydrogen sulfide in anaerobic methane fermentation biogas, which is beneficial for subsequent use of biogas.    DETAILED DESCRIPTION - Increasing the stability of alcohol production comprises:    (A) mixing crushed starch raw materials with last batch of anaerobic outflow water, which is removed with ammonia, where mass ratio of starch raw material to anaerobic outflow water is 1:1.5-5, and tap water is used as replenishment when anaerobic outflow water is not enough;    (B) liquefaction comprising using acid or alkali to regulate the pH of the material liquid at 5.8-6.5; adding liquefying enzyme; and heating and extracting the solution for starch liquefaction;    (C) saccharification comprising after liquefaction, cooling the liquefying liquid at 58-65 degrees C; using acid to regulate the pH of the liquefying liquid; and adding saccharifying enzyme for saccharification for 0-60 minutes;    (D) fermentation comprising further cooling the material liquid at 28-32 degrees C and inoculating liquid yeast (6-15 vol.% of the volume of the material liquid); or directly adding active dry yeast (0.01-1.0 g/L) and controlling the fermentation temperature at 28-38 degrees C;    (E) distilling the fermented liquid to obtain alcohol;    (F) removing sulfate by adding 0.01-0.1 mol/L calcium salt into alcohol distilled waste liquid for sulfate precipitation;    (G) adding alcohol distilled waste liquid into an anaerobic reactor for methane fermentation;    (H) ammonia removal by adding alkali into anaerobic outflow water obtained via anaerobic methane fermentation; regulating pH of anaerobic outflow water at 8.5-10.5; and removing ammonia; and    (I) treating anaerobic outflow water removed with ammonia; and returning to step (A) for recycling.