Abstract: Based on the direct-shear tests and unconsolidated-undrained triaxial tests, the authors study the relationship between shear strength and water content of loess in West Shanxi Province. The experimental results show that the value of shear strength decreases as the water content increases in direct shear test, when water content is smaller than about 12%, the value of cohesion decreases quickly as water content increases. And with water content between about 12% and 23%, it decreases slowly as the water content increases. When the water content is lager than about 23%, it decreases quickly again. The value of internal friction angle has no obvious change as water content increases. The value of internal friction angle ranges from 14° to 32°. In triaxial compression test, shear strength parameter "c" decreases when the water content increases. With the water content less than 12%, the decreasing tendency is steep, and it is slow as the water content is larger than about 12%. With the water content increasing, internal friction angle decreases linearly and has a good correlation.