We aim to investigate the long-term adverse effects of polycyclic aromatic hydrocarbons (PAHs) exposure on heart rate variability (HRV) reduction, and to assess the potential role of transforming growth factor-beta1 (TGF-beta1) in such relationship. We enrolled 2985 adult residents with 4100 observations who participated at baseline and 6-years follow-up from Wuhan-Zhuhai cohort. Ten detectable urinary PAHs metabolites and two HRV indices were repeatedly measured at baseline and follow-up; and plasma TGF-beta1 levels were also determined for all subjects. We observed that both total urinary low molecular weight PAHs (SigmaLWM OH-PAH) and total urinary high molecular weight PAHs (SigmaHWM OH-PAH) were negatively associated with HRV reductions (P < 0.05). Subjects with persistent high levels of SigmaHWM OH-PAH had a significant reduction in HRV over 6 years, and the incensement of TGF-beta1 could aggravate above adverse effects in a dose-response manner. All kinds of PAHs were positively associated with plasma TGF-beta1 elevation, which in turn, were negatively related to HRV indices. Increased TGF-beta1 significant mediated 1.34-3.62% of PAHs-associated HRV reduction. Our findings demonstrated that long-term high levels of PAHs exposure could cause HRV reductions, and TGF-beta1 may play an essential role in such association.