The invention discloses a preparation method of a tri-imine thiazole derivative, and belongs to the technical field of organic synthesis. The method comprises the steps that thiourea and isocyanide are added into a reactor and stirred at room temperature under the action of nickel acetylacetonate (Ni(acac)2) until a reaction is finished, a large quantity of solids are separated out, filtration is conducted, washing is conducted with methanol, drying is conducted, and a target compound is obtained. The preparation method of the tri-imine thiazole derivative is scientific and reasonable and has the advantages that solvent is green, a synthesis method is simple, the reaction time is short, the yield is high, aftertreatment is easy, and a product is easy to purify. The method has the following reaction equation (please see the equation in the description).