A chemical kinetic mechanism for a three-component fuel composed of iso-octane/n-heptane/ethanol has been developed. The mechanism consists of 51 species and 204 elementary reactions. Two elementary reactions that significantly affect laminar flame speed are subjected to sensitivity analysis. The validated results show that the predictions using the present mechanism are in good agreement with the experimental ignition delay time and laminar flame speed. Both the chemical reaction and the transportation process are accurately reproduced by the simulation using the present model in iso-octane/air premixed flames and in n-heptane/air counterflow partially premixed flames. The chemical kinetic mechanism is applicable to multidimensional computational fluid dynamics simulations of the combustion of gasoline surrogates or the cocombustion of primary reference fuels (PRF) with ethanol because of its smaller number of species and fewer reactions.