Abstract: Experiments were conducted to measure water consumption of drip-irrigated cotton and corn under mulch at Xiao Ba Kou Irrigation Experimental Station of Minqin County in 2001. Based on the measured crop water consumption under the condition of sufficient water supply, the water requirements of crop and crop coefficients in the field with drip-irrigation under mulch were investigated. Monthly crop coefficients of drip-irrigated cotton and corn under mulch by FAO Penman-Montieth ET estimation method were determined. The results of this study provide crop coefficients for irrigation scheduling of drip-irrigated cotton and corn under mulch in arid regions.