A numerical analysis of turbulent premixed jet flames within the thin laminar flamelet regime is described. An existing turbulent boundary layer model was used with a modified source term for reaction progress variable. The source term involves laminar burning velocity in order to account the effects of fuel equivalence ratios. The source term includes additional parameters which were obtained by matching with the measurements at φ=3.57, Re=40,000. Test results of the model were compared with existing measurements of turbulent premixed jet flames. The proposed model describes accurately the effects of fuel equivalence ratios on reaction progress variables, turbulent burning velocities, mean axial velocities on burner axis and axial velocity fluctuations. However the model slightly underestimated the measurements.