In this study, the combustion characteristics of coaxial nonpremixed flames of Natural gas and Biogas are investigated numerically. A numerical analysis has been presented to show the variation in the flame structure, flame temperature and formation of soot and NO in the biogas air laminar nonpremixed flames with different biogas composition with the variation in burner loading and fuel jet velocity. It has been observed that with the increase in the CO₂ percentage in the biogas composition, the flame length reduces corresponding to the constant fuel jet velocity condition. However, at constant burner loading, the flame length increases with the variation in the fuel jet velocity, but composition remains the same. The variation of flame length against the methane mass fraction and fuel jet velocity in the inlet fuel stream is directly related to change in methane flow rate. The lower temperature in the flame results in the lower formation of soot and NOx when the mass fraction of CO₂ is increases in fuel composition.