The invention discloses a preparation method of a viscoelastic fluid-based copper nanofluid, relating to a preparation method of a nanofluid. The invention aims at solving the technical problem that the resistance of the fluid is increased during the flow process due to the addition of solid particles in an existing nanofluid system. The preparation method is as follows: adding hexadecyl trimethyl ammonium chloride into distilled water, stirring till complete dissolution, standing, adding nano-copper powder, performing ultrasonic oscillation, then adding sodium salicylate, and stirring to obtain the viscoelastic fluid-based copper nanofluid. The viscoelastic fluid-based copper nanofluid prepared by the preparation method disclosed by the invention can be applied to actual pipelines with the pipe diameter of 0.5cm-50cm and the flow Reynolds number range of 5000-80000. The viscoelastic fluid-based copper nanofluid disclosed by the invention can overcome the shortcomings that the heat transfer of the viscoelastic fluid is worsened and the flow resistance of the nanofluid is increased, and achieve the effects of reducing the flow resistance and enhancing the heat transfer in a flow heat transfer system. The preparation method disclosed by the invention belongs to the field of preparation of the nanofluid.