Objective To evaluate the effects of mass immunization campaign on the epidemiological characteristics of measles. Methods Comparison was made between the incidences of measles before and after the mass immunization campaign in 2007 in Shunqing prefecture of Nanchong city. Results The total number of the reported measles cases reached 460 during 2004 to 2007 in Shunqing prefecture of Nanchong city, and the respective annual rates of incidence were 4.04, 23.53, 11.84, and 33.57, respectively per 100 000 heads. Cases reported from April to July accounted to 73.91% of the total (340/460). Children under 15 were reported to have the highest incidence rate and accounted to 83.70% of the total (385/460), of which incidences of children under 1 accounted to 0%, 10.81%, 13.51% and 25.82%, respectively. Only 20.00% of the subjects (92/460) in this study had a definite history of measles vaccination. After the mass immunization campaign in September, 2007, only 10 cases were reported in 2008 and the incidence rate was 1.58 per 100 000 heads, a 95.29% decrease in incidence rate in comparison with that of the last year. Conclusion The mass immunization campaign has achieved substantial results.