The potential adverse health effects of acrylamide have drawn worldwide attention and the World Health Organization has urged further urgent studies on its health threat. Herein we explored the exposure-response relationship and underlying mechanism between internal acrylamide exposure and heart rate variability (HRV) alteration, a marker of cardiac autonomic dysfunction. We measured six HRV indices and two urinary acrylamide metabolites (N-Acetyl-S-(2-carbamoylethyl)-l-cysteine, AAMA; N-Acetyl-S-(2-carbamoyl-2-hydroxyethyl)-l-cysteine, GAMA) for 2997 general Chinese adults from the Wuhan-Zhuhai cohort, of whom 2414 had data on plasma transforming growth factor-beta1 (TGF-beta1). The associations among urinary acrylamide metabolites, HRV and TGF-beta1 were evaluated by linear mixed models and restricted cubic spline models. The mediating role of TGF-beta1 was investigated by conducting mediation analysis. We found significantly negative dose-response relationships of all urinary acrylamide metabolites and TGF-beta1 with all six HRV indices after adjusting for potential confounders (all P鈥?鈥?.05). Urinary GAMA (beta=0.074, P鈥?鈥?.05) rather than AAMA (beta=0.024, P鈥?鈥?.05) was positively and dose-dependently associated with TGF-beta1, which in turn significantly mediated 5.71-7.41 % of the GAMA-associated HRV reduction. Our findings suggest for the first time that daily exposure of general population to acrylamide is associated with cardiac autonomic dysfunction, where a mechanism involving TGF-beta pathway may be involved.