Soil moisture sensors are used to measure soil moisture content so as to guide irrigation,which has great significance for improving water use efficiency and crop yield.This study presents the best water condition for enhancing both the yield and the water use efficiency in tomato-planting field,and determines the optimal soil depth for burying soil moisture sensors.The results show that it is the optimal water condition for tomato growth when the lower limit of soil moisture content is 60% of field capacity at flowering and fruit bearing stage and 75%of field capacity at fruit stage;and meanwhile,the soil moisture content at 10-20cm layer may better represent the mean soil moisture content of the designed irrigation layer(R²>0.95and 0.85 for flowering and fruit bearing stage and fruit stage,respectively),so it is more reasonable to bury soil moisture sensors in the depth.