Abstract: Soil-water characteristic curve (SWCC) in unsaturated soil mechanics presents the relationship between water content and suction in the soil. The paper introduces six methods with their suitable application ranges. The volumetric pressure plate can measure the matric suction value of less than 1500kPa on wetting and drying SWCCs. The temple apparatus can measure matric suction range from 0 to 100kPa. Matric suction and total suction can be tested with filter paper. The dew-point potentiometer can be used to measure total suction, especially osmotic suction. The TDR probe is the same with matric suction less than 300kPa. The triaxial test system for GDS can be used to test SWCC. The test range lies on the air-entry value. It has a great significance for SWCC since it can be used in exact mathematic models to predict mechanics properties, coefficient of infiltration, shear strength and analysing stability of slope for unsaturated soil. It is very difficult to attain the curves accurately, which are affected by many additional factors . It is an alternative idea to predict SWCC with pore-size distribution and grain-size distribution.