Deficit mulched drip irrigation (DMDI) is globally adopted to address the challenge posed by water resource shortages and increasing food demands under climate change. However, the effect of DMDI on grain crop yield and water productivity (WP) under various management practices, climatic conditions, and soil properties remains unclear. Thus, we conducted a comprehensive meta-analysis of 1071 field observations from 66 published studies to investigate how management practices, climatic conditions, and soil properties influence grain crop yield and WP under DMDI. Results showed that DMDI can reduce the risk of grain crop yield reduction and significantly increase WP by 8.5 % compared with full mulched drip irrigation (FMDI) (p < 0.05). Mean annual precipitation (MAP), water deficit degree, and emitter flow rate were identified as the main drivers of grain crop yield, while mulch method, MAP, and deficit timing were the key driving factors for WP. Structural equation modeling (SEM) revealed that management practices had direct effects on grain crop yield and WP under DMDI, with standard path coefficients of 0.22 (p < 0.001) and 0.07, respectively. Adopting plastic flat mulching with low degree (80-100 % irrigation amount of FMDI) can partially mitigate negative effects of water deficit on grain crop yield and maintain higher WP. Meanwhile, climate factors and soil properties also had significant effects on grain crop yield and WP, with standard path coefficients of 0.15 (p < 0.001) and 0.42 (p < 0.001), 0.24 (p < 0.001) and 0.21 (p < 0.001), respectively. Based on the available data, predominantly from Asia, DMDI is most appropriate for regions with MAP > 250 mm and loamy soils with soil bulk density (SBD) <= 1.4 g cm(-3) and soil organic carbon content (SOC) > 10 g kg(-1). Our findings provide theoretical and technical support for optimizing DMDI in grain crop production to collaboratively improve grain crop yield and WP.