The invention relates to the technical field of utilization of a manganese-containing waste liquid generated by producing hydroquinone, and in particular relates to a method for producing manganese nitrate and co-producing potassium sulfate and ammonium nitrate by using a manganese-containing waste liquid generated by producin hydroquinone. The method mainly comprises the following steps: leaching the waste liquid generated by producing the hydroquinone through a leaching machine so as to obtain a filtrate, and carrying out distillation filtration on the filtrate; carrying out deep processing on a filter cake so as to obtain the manganese nitrate product; and distilling the filtrate at reduced pressure, and then respectively carrying out further deep processing on the distilled filtrate so as to respectively obtain the potassium sulfate and ammonium nitrate products. By using the method, the waste liquid can be clearly treated, and the pollution of the waste liquid on environment is alleviated; and the method has the advantages of obvious social benefits and economic benefits as well as simple process and production equipment, thus the method is a practicable processing and utilizing method.