Abstract: The calculation of intergranular suction is a key factor concerning the study on the effective stress principle of unsaturated soils. First, taking into account the cementing area between soil particles, a simplified ideal model for granular interaction in the microscopic state is established, the relation among various stresses on soil particle contact points is derived, and two typical ways for macroscopic accumulation soil particles are analyzed. Then a unified expression for intergranular suction is proposed. Second, the effect of cementing between soil particles area on the intergranular suction is discussed. The results show that employing the surface tension component directly can simplify the calculation of intergranular suction. Finally, a case study demonstrates the existence of the cementing area between soil particles has an important influence on the intergranular suction. Besides, based on the double effective stress hypothesis in porous media, a double effective stress formulation for unsaturated soils under low water content is obtained. The aim of the study is to provide a novel idea for calculating the effective stress of unsaturated soils.