The invention discloses a nano carbon material/polyamide microsphere composite material and a preparation method thereof. The preparation method comprises the following steps: pre-dispersing a nano carbon material in a molten polyamide monomer; adding other polymers or monomers as a dispersion phase or a continuous phase, blending, then adding a catalyst, an activating agent and an auxiliary agent, then preparing a nano composite material by adopting an in-situ polymerization process, and finally dissolving and drying the nano composite material with a solvent to obtain the powdered nano carbon material/polyamide microsphere composite material. According to the preparation method, pre-dispersing of the nano carbon material in the molten polyamide monomer is realized by adopting power ultrasound and the like; the nano carbon material is well dispersed in the polyamide monomer, so that the nano carbon material is uniformly dispersed in the polyamide microsphere composite material, the electric conductivity, the heat conductivity and the mechanical property of the polyamide microsphere are greatly improved, and the application field of the polyamide microsphere is further widened.