NOVELTY - A threonine mother liquid is processed by centrifuging threonine mother liquor, filtering, recycling the filter cake comprising bacterial body protein, and collecting the filtrate; heating the filtrate, filtering the filtrate using a membrane, recycling the filter cake, and collecting the filtrate; and mixing the obtained filter cakes, adding hot water, enzymolyzing, adding sulfuric acid, adding lysozyme, acid protease and beta -D-glucanase, enzymolyzing, centrifuging, filtering, and packing the filter cake.    USE - Method of processing a threonine mother liquid.    ADVANTAGE - The method is simple, utilizes waste thus reducing pollution, has low energy consumption, produces less wastewater, reduces investment cost, and prolongs service life of equipments.    DETAILED DESCRIPTION - A threonine mother liquid is processed by:    (A) centrifuging threonine mother liquor at a speed of 4000-5000 revolutions/minute, filtering, recycling the filter cake comprising bacterial body protein, and collecting the filtrate;    (B) heating the filtrate at 37 degrees C and pressure of 2 bars, filtering the filtrate using a membrane having an aperture of 40 nm, recycling the filter cake, and collecting the filtrate;    (C) mixing the obtained filter cakes, adding hot water to obtain a solution having a solid content of 8%, enzymolyzing at 55 degrees C, adding sulfuric acid to adjust pH value to 6.5, adding (kg/m3) lysozyme (10), acid protease (25) and beta -D-glucanase (5), enzymolyzing for 6 hours, centrifuging, filtering, and packing the filter cake;    (D) subjecting filtrate to three-effect plate type evaporator controlled at low temperature to obtain paste having dry basis content of higher than 65%, concentrating, setting aside to form precipitate, filtering, and subjecting filtrate to ultrafiltration membrane, desalting the filtrate; and    (E) subjecting to bipolar membrane electrodialysis at 26 degrees C, operating voltage at 50 V, single film area of 500 cm2, membrane thickness of 10 cm and electrode and film distance of 0.5 cm, subjecting to multi-effect plate type evaporator to obtain product having a concentration of 1.2 g/cm3, subjecting solution to cation exchange column, and evaporating the concentrating the liquid.