Objective:to do a population study with MMSE in rural area of north China.Method:13 962 farmers aged 55 or above from four villages in Linxian of Henan province were tested with MMSE, with 3 different cut-off points according to different level of education in our sample.Result:in our sample, the average total score of MMSE was lower than Chinese norm, especially that of calculation. Those aged, with poor education, female, with low SES had lower scores in MMSE test. There was a negative correlation between score of MMSE and that of ADL (acitivity of daily living).Conclusion:female, age, poor education, low SES are risk factors for dementia.