The invention provides an environment-friendly high and low temperature resistant and oil resistant flame-retardant nano-composite thermoplastic elastomer and a preparation process thereof. The nano-composite thermoplastic elastomer is prepared from the following components in parts by weight: 60 to 75 parts of NBR (Nitrile-Butadiene Rubber) nano-composite particles, 25 to 40 parts of PVC (polyvinyl chloride) premolding powder, 10 to 15 parts of modifier ABS (Acrylonitrile Butadiene Styrene), 10 to 15 parts of first flame retardant, 5.0 to 10 parts of second flame retardant, 0.8 to 1.2 parts of activating agent, 0.2 to 0.4 part of vulcanizing agent, 0.8 to 1.2 parts of anti-aging agent, 0.5 to 1.0 part of accelerator, 0.3 to 0.5 part of ultraviolet light absorber and 1.0 to 2.0 parts of processing aid. The thermoplastic elastomer provided by the invention is green and environment-friendly, resistant to ozone and excellent in mechanical property, high and low temperature resistance, oil immersion resistance and flame retardance and can be used for sheaths and shoes of flame-resistant, oil-resistant and heat-resistant flexible wires, elastomer cables, oil-resistant heavy flexible wires, movable cables and the like, as well as oil pipes and the like.