Abstract: Objective To explore the difference in the prevalence and risk factors of essential hypertension(EH)between Yi farmer and Yimigrant.Methods A representative sample of 2 966 Yi people aged 16 to 76 years were randomly selected in Sichuan province,China,2007-2008.EH was diagnosed according to the WHO criteria.Questionnaire survey,anthropometric measurement and bloodtest were carried out,and logistic regression analylsis was used to study the related risk factors.Results The prevalence of EH in Yi farmers was 3.19%(male:4.73%,female:1.92%),and that of Yimi grants was 15.0%(male:17.74%,female:10.83%).The borderline hyper tension prevalence in Yi farmers was 12.53%,and that of Yimig rants was 25.9%.For Yi farmers,age and diabeteswere the risk factors of EH.For Yimigrants,age and fat/overweight were the risk factors of EH,and hyperuricemia was a protective factor.Conclusion With the change of environmental condition,the risk of EH become shigher when Yi farmers migrate to town.