The invention relates to a synthetic method for isopropyl hydrazine. The synthetic method is characterized in that isopropylhydrazine hydrochloride is prepared by making hydrochloric acid hydrazine react with isopropanol under the protection of inert gas, coarse isopropyl hydrazine is prepared through hydrazine-hydrate-free isopropyl hydrazine hydrochloride, and isopropyl hydrazine is obtained through distillation and refining. The synthetic method has the advantages that the process route is short, and yield reaches about 95%; the raw material cost is low, internal recycle of hydrochloric acid hydrazine is achieved in the flow, the output of sewage is reduced, and no by-product is generated; pure water washing agents are adopted for isopropyl hydrazine instead of distillation and purification, and therefore the energy consumption is lowered; the hydrogenation reaction is replaced with the new process, and the safety coefficient is increased.