In this study, we found that the prevalence of RASSF1A promoter methylation and the risk to ESCC in ESCC patients with the age of more than 50 years old were higher than those with less than 50 years old (OR=3.11, 95% CI=1.10–8.73), which further indicate the impact of environmental factor in terms of exposure time on RASSF1A promoter methylation. The gene discussed is RASSF1; the disease is esophageal squamous cell carcinoma.