The invention belongs to the technical field of a nano material and a nano technology, and more specifically relates to a controllable preparation method of a Cu2ZnSnS4 nano-crystalline material. The preparation method comprises the following steps: adding copper acetate, zinc acetate and stannic chloride in oleylamine, introducing argon as protection gas, stirring copper acetate, zinc acetate and stannic chloride under certain temperature for completely dissolving the materials to obtain a complexation solution of metal salt; heating the complexation solution of metal salt to set temperature, adding a diphenyl ether solution of thiocarbanilide; after the reaction is complete, cooling the material to the room temperature, cleaning the reaction products by methanol to obtain the Cu2ZnSnS4 nano-crystalline material. The method selects thiocarbanilide as a sulfur source, employs a heat injection method to prepare the Cu2ZnSnS4 nano-crystalline material, the Cu2ZnSnS4 nano-crystalline material is obtained by controlling the addition proportion of the precursor, and the Cu2ZnSnS4 nano-crystallines with different size is obtained by controlling the reaction temperature and the reaction time.