The invention discloses a method for preparing a concentrated liquid 
fertilizer by using 
wastewater containing 
livestock excrement. The method comprises the following steps: adding acids to immobilize amino and keep fertilizers; adding quicklime to neutralize excessive acids; performing primary 
fermentation so as to increase the 
dissolution degree of organic fertilizers; performing 
solid-liquid separation; performing negative-pressure concentration; and performing secondary 
fermentation on a concentrated liquid, thereby obtaining a 
livestock excrement concentrated liquid 
fertilizer. The method is simple in concentration process, good in 
operability and low in concentration cost; the solution degree of 
fertilizer components in the organic liquid fertilizer is high; due to amino immobilization and fertilizer increase of acids, and 
alcohol for increasing the 
dissolution degree of 
livestock excrement in the 
wastewater, the organic fertilizers can be relatively thoroughly dissolved in the 
wastewater, the cost of negative pressure concentration is reduced, the 
alcohol and the water can be both recycled, and the 
utilization rate of the livestock excrement is effectively increased; and by adopting the method, wastewater containing livestock excrement generated in the on-scale 
livestock breeding process can be turned into a high-concentration 
organic fertilizer, so that wastewater treatment in the on-scale 
livestock breeding process is solved, and harmonious development of 
agriculture, on-scale 
livestock breeding and living environments of people is promoted.