As turbulent combustion is commonly used in industrial applications, in this study, a new burner is designed in order to be applied in a test furnace. With the employment of Fourier, transform infrared (FTIR) spectroscopy, the species in the flue gas at different ratios of direct secondary air flow and swirling secondary air flow are detected to choose the optimum ratio for the subsequent experiments. An experimental investigation is performed to study the effects on a CH4/air swirling turbulent flame while mixing CO2 with CH4 as the fuel. The OH-PLIF (hydroxyl-planar laser-induced fluorescence) and FTIR methods were employed to measure the OH distribution and NO in the flue gas separately with the added CO2. To study the reaction mechanism and predict the flow, temperature fields, and NOx emissions, numerical modeling works have been performed employing the COMMENT code. The standard k-epsilon and Reynolds stress model turbulence models are used to describe the turbulent flow. The "eddy dissipation" model (6 species and 2 reactions), the PDF (probability density function) model (beta function) (9 species and 8 reactions) with a chemical equilibrium model, and the laminar flamelet model (17 species and 46 reactions) are used for modeling the turbulence-chemistry interaction. The NOx postprocessor is used to predict the NO emissions. The concentrations of the OH and O radicals are obtained by assuming the hypothesis of partial equilibrium and using a PDF in terms of temperature. Several factors influencing the combustion process are investigated. From the experiments, it was found that the OH and NO production both increased first, reached a peak value when the fraction of CO2 was 25%, and then decreased. The numerical results obtained are compared with the experimental results and the results from previous works, and the experimental and numerical results are found to be in good agreement.