The invention discloses an environment-friendly flame-retardant rubber for shoe soles and a preparation method thereof. The environment-friendly flame-retardant rubber for shoe soles comprises the following components in parts by weight: 55-65 parts of 2# standard rubber, 8-12 parts of styrene-butadiene rubber, 25-35 parts of cis-1,4-polybutadiene rubber, 1-3 parts of sulfur, 2-4 parts of accelerator, 1-3 parts of stearic acid, 4-6 parts of nano zinc oxide, 0.5-0.7 part of releasing agent, 54-66 parts of reinforcing filler, 15-21 parts of softening system, 18-22 parts of red phosphorus, 4-6 parts of nitrogen-based flame retardant MCA (melamine cyanurate) and 18-22 parts of nitrogen-phosphorus flame retardant. In the invention, the natural rubber, styrene-butadiene rubber and cis-1,4-polybutadiene rubber are used as the main materials, the reinforcing filler and softening system are added to ensure the physical properties of the rubber, thereby ensuring the service life of the rubber sole, and the red phosphorus, nitrogen-based flame retardant MCA and nitrogen-phosphorus composite flame retardant NPR (nitrogen and phosphorus retardant) are together used as a flame retardant system, thereby providing excellent flame retardancy for the product. The invention has the advantages of simple method, low cost and favorable use effect.