The invention relates to a preparation method of a high-temperature resistance and puncture resistance thermoplastic polyurethane elastomer. The preparation method comprises the following steps of adding an antioxidant, a catalyst and polyester polyol into a reaction kettle for reaction to form a component A, heating and melting diisocyanate to form a component B, mixing a dihydric alcohol chain extender and trimethylolpropane for reaction and dehydration to form a component C, simultaneously pouring and adding the component A, the component B and the component C at a certain mass ratio into an extruder for the reaction, quantitatively adding multiwalled carbon nanotube powder into the extruder via a high-precision weight loss weigh, uniformly mixing with polyurethane melt of which the reaction is basically finished, and preparing a high-temperature resistance and puncture resistance thermoplastic polyurethane elastomer particle via a granulator. The high-temperature resistance and puncture resistance thermoplastic polyurethane elastomer prepared by the preparation method has physical properties of still keeping high strength and high tear strength in a high-temperature environment.