This paper presents a dimension reduction technique for turbulent non-premixed flames based on a chemical equilibrium method combined with a reaction calculation. An advantage of the proposed technique is that it simplifies the process of building a reduced chemical mechanism according to the accuracy requirement for the chemical species. The proposed technique reduces the computational time for the combustion simulation. In this technique, chemical species are roughly divided into two groups: The first includes fuels and intermediate species; the intermediate species include only those necessary for high accuracy. The second group comprises the rest of the species, and their mass fractions are obtained from a look-up table prepared using chemical equilibrium calculations conducted prior to the combustion simulation. The obtained results were compared with the experimental data of a CO-H2-air turbulent non-premixed flame and computational data obtained using the eddy dissipation concept (EDC) model. The major mass fractions of CO, H2, and H2O, as well as the temperature and mixture fraction obtained using the proposed technique, were in good agreement with these reference data. Furthermore, compared with the EDC model, the minor mass fractions of OH, O, and NO obtained using the proposed technique were close and the computational time was 75% lower.