Abstract: Objective To explore the reason for high measles incidence rate in Tianjing city from 2004 to 2008 for measles control.Methods The antibody level,nosocomial infection of mesales were analyzed with the data of measles surveillance and investigation.Results The measles incidence rate increased from 0.67/10⁵ in 2004 to 21.97/10⁵ in 2008 and the incedence rate of <1 year age group was the highest.More than 50% of all cases in 1-6 year age group occured in floating population.There were 28 mesales outbreaks in 2005-2008,and 13 outbreaks in companies.Nosocomial in fection was one of risk factors of measle s(odds ratio=4.0,95% confidence interval=17.2-97.8).In 2007,the an tibodie spositive rate of measles was 91.78% in healthy people and the protective rate was 75%.Conclusion The major reasons for measles epidemic in Tianjin were low immunization coverate of measles vaccine,accumulation of unvaccinated people,secondary mimunization failure,nosocomial infection,and the increase of floating people.