The aim of this research is to study the effect of gas phase on the effective thermal conductivity of heterogeneous materials with high solid phase mass fraction. A general model based on Maxwell-Eucken model and Effective Medium Theory model was proposed first and compared with the previous models, showing some potential significance of the present model. The present model shows that the gas phase in heterogeneous materials is significantly affected by maximum volume fraction of solid phase. Then, the effect of the shape parameters of solid particle on the maximum volume fraction of solid phase was discussed. The results indicate the maximum volume fraction of solid phase tends to grow up by increasing the particle diameter or decreasing the particle diameter ratio. Finally, the effective thermal conductivity of heterogeneous materials predicted by the proposed model was compared with that by direct experiment, showing great agreement. (C) 2015 Elsevier Ltd. All rights reserved.