Objective：To explor the relationship between MiR205 promoter methylation and Barrett’s esophagus cancerous. Methods：The expression of miRNA205 in Barrett’s esophagus，esophageal cancer and normal esophageal mucosa cells before and after demethylation processing was detected by RT-PCR. MiR205 promoter methylation levels were measured by methylation specific polymerase chain reaction（MSP）. Results：miR205 expression was reduced obviously in Barrett’s esophagus and esophageal cancer cells than in normal esophageal，with statistically significant differences（P=0.002）. After demethylation，miR205 expression was sig－nificantly increased in Barrett’s esophagus（BT，B-T10） and esophageal cancer（EC109，TE-10，SEG-1） cells，with statistically sig－nificant differences（P=0.000）. MSP showed miR205 promoter changes to be low-methylation or non-methylation. Conclusion：Re－duced expression of miR205 in Barrett’s esophagus and esophageal cancer cells is related to its promoter methylation. Throughout the carcinogenesis of Barrett’s esophagus，miR205 promoter methylation may become a key molecular biomarker in process of Barrett’s esophagus canceration and may become the prevention and treatment targets of Barrett’s esophagus canceration.