Soil moisture is an important factor for plant growth and development in arid and semiarid areas． We used three methods of drying methods，TDR(time domain reflectometry) and EC-5 sensor to observe soil moisture variations in the Mu Us sandy land． The results show that there was no significant difference in the soil moisture contents measured using the three methods in different layers． The values from the three methods were significantly correlated．EC-5 sensors could be used in observation low water contented soils with a precision level similar to traditional methods like drying and TDR． Furthermore，EC-5 is more suitable in developing an automated soil moisture monitoring network．