NOVELTY - Producing potassium bisulfate, comprises (i) measuring potassium chloride and 98% concentrated sulfuric acid added into a spiral conveying machine synchronization with a reactor, and passing steam into the reactor at a pressure of 0.6 Mpa; and (ii) continuously adding potassium chloride and sulfuric acid into the reactor, continuously stirring, mixing to carry out side reactions, and taking out hydrogen chloride gas produced during the reaction by an exhaust fan to carry out hydrochloric acid absorption process, and allowing potassium bisulfate solution to flow into a mixed acid groove.    USE - The potassium bisulfate is useful in the preparation of fertilizer (claimed).    ADVANTAGE - The method utilizes low cost of raw materials, and agricultural waste; performs nitrogen fixation with good water retention performance; reduces the utilization rate of fertilizer; and simultaneously saves energy, and is environmental friendly; and achieves the conversion of waste into useful materials.    DETAILED DESCRIPTION - Producing potassium bisulfate, comprises (i) measuring potassium chloride and 98% concentrated sulfuric acid added into a spiral conveying machine in synchronization with a reactor, where the mol ratio of potassium chloride and 98% concentrated sulfuric acid, is 1.1:1, and passing steam into the reactor at a pressure of 0.6 Mpa at 105 degrees C; and (ii) continuously adding potassium chloride and sulfuric acid into the reactor, continuously stirring, mixing to carry out side reactions, and taking out hydrogen chloride gas produced during the reaction by an exhaust fan to carry out hydrochloric acid absorption process, and allowing potassium bisulfate solution to flow into a mixed acid groove. An INDEPENDENT CLAIM is also included for preparing fertilizer, comprising (a) taking potassium bisulfate prepared as mentioned in the steps (i) and (ii); and (b) mixing mixture of potassium bisulfate solution and phosphoric acid in an acid groove, added in a mass ratio of 2:3, uniformly stirring by a stirring paddle to obtain mixed acid, and pumping the mixed acid into a granulation unit, and granulation, and drying by spraying liquid ammonia, and cooling to room temperature, and spraying an organic auxiliary agent, uniformly stirring using a stirrer, and drying at low temperature to obtain the product, where mass ratio of mixed acid, liquid ammonia and organic auxiliary agent, is 10:3:1, and the organic auxiliary agent is prepared by drying wheat straw, crushing using a crusher, adding into a fermentation tank, and then adding soybean meal into the fermentation tank, and uniformly stirring wheat bran and water at 100 degrees C, and reducing temperature to 30 degrees C, and adding a composite bacterial solution, stirring for 100 rotations/minute, fermenting for 48 hours, to obtain the fermentation liquid, and the mass ratio of straw powder, soybean meal, bran, water and mixed bacterial liquid, is 10:3:3:50:1, and the composite bacterial liquid includes Bacillus megaterium liquid, Bacillus licheniformis liquid, Trichoderma liquid and round brown solid nitrogen-fixing bacterial liquid, in a volume ratio of 1:1:1:1, and the concentration of the four bacterial liquids accounts to 1x 108 cells/ml.