OBJECTIVE: To explore the incidence rate of people with mild cognitive impairment (MCI) which transferred to Alzheimer's disease (AD) and to study the related influencing factors. METHODS: 600 MCI aged people were experienced screening test which was conducted by WHO-BCA, MMSE and DCR. A three-year follow-up study was conducted to get the information on the aged people with MCI. Data related to demography, behavior, chronic diseases and perception of the elderly with MCI were collected through face to face interview. Characteristics of the elderly with MCI aged people were tested by 16PF. The content of Apoe was tested by PCR. People with NC were investigated by telephone to get the progression and the time to AD. Methodologies on statistics were log-rank test and Cox proportional hazards regression model. RESULTS: The incidence rate of MCI to AD was 6.53% person-years. The incidence rate of the normal people to AD was 1.24% person-years. The hazard of MCI to AD was 5.27 times (95%CI: 3.01 - 9.82) of the normal people to AD. The result of Cox proportional hazards regression model displayed that:older age (RR = 3.14, 95%CI: 2.98 - 7.46), hypertension (RR = 3.28, 95%CI: 3.02 - 8.48), hyperlipemia (RR = 2.22, 95%CI: 1.29 - 3.82), diabetes (RR = 4.87, 95%CI: 2.56 - 9.25), lack of sports (RR = 2.02, 95%CI: 1.29-3.14), anxiety (RR = 4.46, 95%CI: 3.07 - 8.14), dread fullness (RR = 4.08, 95%CI: 3.52 - 5.25), loneliness (RR = 1.89, 95%CI: 1.13 - 3.16), characteristics of anxiety (RR = 5.07, 95%CI: 2.56 - 10.04, introvert characteristics (RR = 2.05, 95%CI: 1.33 - 3.15) and ApoE4 (RR = 1.73, 95%CI: 1.15 - 2.63) were the risk factors of MCI to AD. Higher education (RR = 0.29, 95%CI: 0.07 - 0.43), intellectual work (RR = 0.14, 95%CI: 0.05 - 0.32), often reading books (RR = 0.30, 95%CI: 0.15 - 0.58), often taking part in recreational activities (RR = 0.41, 95%CI: 0.23 - 0.75) seemed to be the protective of MCI to AD. CONCLUSION: The rate of the elderly with MCI that developing to AD was high, suggesting further study on the cognitive situation among the MCI aged people should be carried out.