Abstract: To investigate effects of magnetoelectric activated water irrigation combined with biostimulants on cotton growth, yield, and water use efficiency（WUE）with drip irrigation under mulch, an effective and feasible approach was provided to improve agricultural irrigation efficiency, promote good-quality and high-yield crop production, and advance green ecological agriculture development．A randomized block experimental design was adopted with three treatments, including conventional water irrigation（T₁）, conventional water irrigation+biostimulant application（T₂）, and magnetoelectric activated water irrigation+biostimulant application（T₃）．Field experiments were conducted to systematically analyze changes in soil moisture content, water consumption during growth periods, growth indicators, yield, and WUE under different treatments．Quantitative characterization of cotton growth indicators was performed using Logistic and rational models, followed by comparative parameter analysis．Results showed that magnetoelectric activated water irrigation enhanced soil water retention, while biostimulant application promoted water absorption by cotton root．Compared to T₁, T₂ and T₃ significantly increased relative chlorophyll content by 3.84% to 6.95% and 5.68% to 16.46%, plant height increased by 6.03% to 25.02% and 10.60% to 37.28%, and leaf area index increased by 11.13% to 19.70% and 21.28% to 36.68%, respectively．During cotton vigorous growth period, dry matter accumulation increased by 13.72% and 19.01%, respectively．Synergistic effects of magnetoelectric activated water and biostimulants significantly enhanced leaf nutrient content and photosynthetic activity．Cotton yield improved by 31.56% and 37.93%, and WUE improved by 22.64% and 24.25%, respectively．Both Logistic and rational models could effectively describe trends in growth indicators such as plant height and leaf area index as effective accumulated temperature changes during growing, and provide practical value for predicting cotton growth．Magnetoelectric activated water with biostimulants application could effectively promote cotton growth, enhance yield, and improve water use efficiency．