Abstract: Objective To investigate the level and significance of smad4 promoter methylation in the Hans and the Kazaks with esophageal squamous cell carcinoma in Xinjiang. Methods We collected 37 cases of ESCC and 33 cases of local normal esophageal tissues of the Kazaks, and 31 cases of ESCC and 33 cases of local normal esophageal tissues of the Hans. Mass ARRAY methylation DNA quantitative analysis technology was used to detect the methylation status of smad4 gene promoter in ESCC. Results The average methylation rates of smad4 gene promoter CpG units were 3.4% in esophageal cancer in the Hans and 2.8% in relevant control group, 3.4% in esophageal cancer in the Kazaks and 2.5% in relevant control group, with no statistically significant difference (P>0.05). The average methylation rates of CpG-15 and CpG-27(4.7%, 4.9%) in smad4 gene in the Hans with ESCC were significantly higher than those in relevant control group (2.8%, 3.5%). The average methylation rates of CpG-1, CpG-16-19, CpG-27-28, CpG-31-33(1.7%, 4.5%, 4.9%, 6.8%) in smad4 gene in the Kazaks with ESCC were significantly higher than those in relevant control group (0.7%, 2.2%, 3.0%, 5.5%). The average methylation rates of CpG-6 in the Kazaks with ESCC and relevant control group (1.9%, 1.1%) were significantly higher than that in the Hans with ESCC(0.4%), with statistically significant difference (P<0.05). Conclusion Smad4 gene promoter hypermethylation may participate in the occurrence of ESCC. Hypermethylation of CpG-15 and CpG-27 in smad4 gene promoter may closely relate with the occurrence of ESCC in the Hans. Hypermethylation in CpG-1, CpG-16-19, CpG-27-28 and CpG-31-33 may closely relate with the occurrence of ESCC in the Kazaks. Hypermethylation in CpG-6 may result in higher incidence of ESCC in the Kazaks than that in the Hans.