A great challenge for agricultural production is to produce more food with less water, which can be possibly achieved by increasing crop water use efficiency (WUE). We systematically reviewed 51 cases from 48 empirical studies with field experimental results on wheat and cotton. We estimated the yield-water use relations under both furrow and micro irrigation systems, compared crop water use to achieve maximum WUE and maximum yield, and evaluated the effects of many influential factors using meta-regression analysis. Our results showed significant effects of micro irrigation adoption, farm management practices focusing on crop, soil and water, and some moderator variables related with the empirical studies on crop WUE. Assessments of the publication selection bias and genuine effects illustrated the application of weighted least squares in conducting meta-regression analysis.