The invention discloses a cold-resistant flame retardant thermoplastic elastomer and a preparation method thereof, solving the problem that the existing thermoplastic elastomer has poor low temperature resistance. The cold-resistant flame retardant thermoplastic elastomer is characterized by being prepared from powdered cis-polybutadiene, polyvinyl chloride, chlorinated polyethylene, powdered acrylonitrile-butadiene rubber, zinc oxide, stearic acid, paraffin oil, sulphur, dicumyl peroxide, triallyl isocyanurate, an accelerator, an anti-aging agent, tribasic lead sulphate, dibasic lead sulphate, an antistatic agent, conductive carbon black, white carbon black, a cold-resistant plasticizer, a liquid fire retardant and a solid fire retardant. The cold-resistant flame retardant thermoplastic elastomer can be used at the temperature of -60 DE C for a long time while good mechanical properties and processability are guaranteed; in addition, the cold-resistant flame retardant thermoplastic elastomer has excellent flame retardant performance and also has the advantages of good elasticity, simple technique, low energy consumption, high production efficiency and recoverability and is a good material for manufacturing products such as a cold-resistant flame retardant conveying belt, a driving belt, a rubber tube, an electric cable, an automobile sealing product and a rail transit shock absorbing product.