Abstract: The basic principle, approach and precautions for measuring both the matric and the total suction of unsaturated soils using the filter paper method are introduced. By means of sodium chloride solutions, the total suction calibration curve of the domestic filter paper, named as “Double-Circle” No. 203, is established and a bi-line regression equation is proposed. As an application, the identical compacted samples of Nanyang expansive soil are tested under different water contents using the filter paper method, and the relationships among the total suction, matric suction, osmotic suction and water content of the expansive soil are established. Furthermore, the SWCC of the expansive soil, with the water content ranging from 16% to 30%, is obtained.