Turbulent diffusion flame is one of the most important driving force for the growth of a fire. Progress in the computer application to the fire safety science and innovation in fire measurement since around 1980 has enabled a precise prediction of the effect of flames to fire growth and its application to the wide range of realistic fire problems. After a short review on the progress of the modeling of turbulent diffusion flames since the beginning of the modem fire safety science, recent examples of the application of diffusion flame modeling to the assessment of structural fire safety, classification of lining materials and full scale tests on wooden large building are introduced.