The invention discloses a method for utilizing marigold flower wastewater. The method is characterized by comprising two steps of neutralization and fermentation, namely adding 0.8-1.0Kg of KOH into 100Kg of marigold wastewater according to the weight, wherein the purity of KOH is required to be not less than 90 percent, and the pH value of the reacted neutralization solution is between 6.5 and 7.0; storing the neutralized neutralization solution in a fermentation tank to obtain the organic liquid fertilizer, wherein the fermentation time is not less than a month under the condition of the temperature of 4-37 DEG C. The organic liquid fertilizer obtained by treating the wastewater generated by the marigold flowers in industrial production in the method serves as an organic fertilizer to be applied to a farmland and is used for crop planting, the wastes are recycled, and the effect of changing wastes into valuable materials is achieved. The problem of pollution of the wastewater on the environment is solved, trouble of wastewater treatment in enterprises is reduced, and a potassium-containing liquid fertilizer is provided for crops.