Abstract Body (Do not enter title and authors here): Background: With the development of industrialization, manganese pollution in the environment has become increasingly common, but the relationship between manganese exposure and heart failure (HF) remains understudied.This study aimed to explore the association between urinary manganese levels and HF.Methods: This study utilized data from the National Health and Nutrition Examination Survey (NHANES) 2011-2018. Among 39,156 initial participants, 32,143 were excluded due to missing records on HF and urinary manganese, leaving 7,013 samples for analysis. Propensity score matching (PSM) was employed to reduce potential confounding effects. Weighted logistic regression models and restricted cubic spline (RCS) curves were used to analyze the association between urinary manganese and HF.Results: Among 39,156 NHANES records, 7,013 met inclusion criteria (mean age 49.45 years [SD 17.53]; 49.29% male). The main cohort was divided into two groups based on median urinary manganese levels, with 695 participants having levels above the median. After 1:1 PSM, 1,386 participants were included (mean age 48.69 years [SD 17.89]; 49.49% male). Groups were balanced except for "Other Hispanic" ethnicity and "Below 9th grade" education. Higher urinary manganese levels were associated with increased likelihood of heart failure (Model 1: OR 1.22 [95% CI 1.03-1.43]; Model 2: OR 1.23 [95% CI 1.09-1.39]; Model 3:OR 1.20 [95% CI 1.03-1.39]). Post-PSM, associations remained consistent (Model 1: OR 1.56 [95% CI 1.21-2.02]; Model 2:OR 1.44 [95% CI 1.03-2.01]; Model 3:OR 1.53 [95% CI 1.04-2.27]). RCS analysis revealed a linear association between urinary manganese levels and HF risk (nonlinear P = 0.139; association P = 0.01). Stratified analyses showed ORs of 1.20 (95% CI 1.03-1.41) for females and 1.23 (95% CI 0.98-1.54) for males. For college or above education: OR 1.42 (95% CI 1.07-1.87); high school or equivalent: OR 1.21 (95% CI 1.02-1.43). For poverty income ratio (PIR) <1.0: OR 1.52 (95% CI 1.23-1.88); PIR 1.0-3.0: OR 1.20 (95% CI 1.00-1.43). For BMI<25 kg/m2: OR 1.38 (95% CI 1.04-1.82). For no physical activity: OR 1.29 (95% CI 1.07-1.56).Conclusions: Urinary manganese concentrations showed a linear positive association with HF risk, particularly among females, those with higher education, lower PIR, lower BMI, and no physical activity. These findings suggest manganese exposure may be an important environmental risk factor for HF, with significant public health implications.