In 2015 China will carry out the fourth oral health survey.This report will introduce the background, purposes, contents and projects of this oral health survey.Many countries in the world like the U.S.and same countries in Europe regularly carry out oral health surveys.These surveys play an important role in evaluating the situations of the prevalence of caries and periodontal diseases, the oral health habits of people of various countries and promotion the prevention of oral diseases in their own countries.Since 1983 China has carried out the first, second and third national oral health survey respectively in 1983, 1993 and 2005.