The invention discloses a synthesis method of zoalene, belonging to the technical field of pharmaceutical engineering. The method comprises the following steps: A. nitration process, B. acylating chlorination process, and C. ammonifying process, wherein in the step A, a process of recycling concentrated sulfuric acid is set, specifically, the collected waste acid is treated by reduced pressure distillation and is concentrated, sulfur trioxide is then added into the treated waste acid, and the newly prepared concentrated sulfuric acid is added into a reaction kettle again for carrying out a nitration reaction; in the step C, a process of recycling waste ammonia water is set. By recycling and reusing raw materials, the method does not cause accumulative increment of sulfuric acid and ammonia water, thus improving the utilization rate of the raw materials and lowering the production cost; furthermore, the method reduces the treatment cost of the waste acid and the waste ammonia water and greatly reduces the discharge amount of waste water, thus having an important significance for environmental protection.