The density fluctuation correlation terms are introduced into modelling of a turbulent flame. A mathematical simulation of the density-scalar parameters fluctuation correlation terms (ρφ) is given in the calculation of combustion. The two transport equations for the density-velocity fluctuation correlation terms (pu and pv) are derived to solve the turbulence characteristics of a homogeneous gas flame and a heterogeneous pulverized coal flame. A further study has been made of the mutually interacting turbulent fluctuation and combustion process.