Abstract: Optimizing water management for vegetable cultivation under facility conditions is essential for both increasing water resource utilization and mitigating regional agricultural water pressure. A two-year experiment was conducted to explore the effects of four soil moisture levels, including 95%~110%, 85%~95%, 70%~80% and 60%~70% of maximum field moisture capacity (FMC), on tomato yield, flavor quality along with water and fertilizer utilization in polytunnel in arid-plateau region of East of Shanxi. The highest biomass and fruit were produced by 85%~95% FMC and 70%~80% FMC among all treatments. Relative to FMC 95%~110%, FMC 85%~95% and FMC 70%~80% increased fruit yield by 8.3%~23.0% and 6.5%~7.5%, respectively. As soil moisture content decreased, the levels of soluble sugars, nitrates, and titratable acidity in the fruit were enhanced, whereas the Vitamin C content inhibited. A total of 375 volatile organic compounds (VOCs) were detected by HS-SPME-GC-MS. There were same VOCs in terms of primary classification of metabolites for different soil moisture levels; whereas they influenced the relative content of different volatile metabolite class. Enhanced percentage of ketones, aldehydes and acid in VOCs were notable by low soil moisture content. Further relative high contents of ketones and aldehydes were induced by low soil moisture content. The treatments of FMC 70%~80% and FMC 60%~70% exhibited distinguished higher levels of sweet, bitter, aldehydic, citrus and fatty odour characteristics compared to FMC 95%~110% treatment. Given that PLS-DA analysis did not exhibit an obvious discrimination in terms of volatile metabolite class between FMC 70%–80% and FMC 60%–70% treatments, the suitable soil moisture content for achieving both superior flavor and high yield of tomatoes in this region is recommended to be FMC 70%–80%.