The purpose of this paper is to find out the correlations between turbulence conditions and heat release in the turbulent diffusion flames of comparatively simple characteristics of turbulence. First, a model of combustion progress is proposed, having the two fundamental concepts Namely, (1) the turbulence is isotropic and never grows by combustion, (2) the combustion progress corresponds to the progress of disruption of fuel pockets by the turbulence agitation. The analytical treatment of the model shows that the heat release is related to the ratio of the burning duration to the characteristic time of initial turbulence and to the Reynolds number of flame. The experiments also show that the results are qualitatively correct and, moreover, reveal the size effects and the influences of air-fuel ratio.