Caries is a multifactor dynamic infectious disease with bacteria as the main factor and can affect the development of both deciduous teeth and permanent teeth. According to the fourth national oral health epidemiological survey, the prevalence rate of early childhood caries (ECC) in 5 - year- old children reached 70.9% , showing an upward trend. Understanding the etiology and epidemiological characteristics of ECC is of great significance in preventing the occurrence and development of ECC. This article reviews the epidemic status, etiology and related factors of ECC. The results of a literature review show that the prevalence of ECC in China is high and regional differences are large. The main related factors include biological factors, behavioral habits factors, social and economic factors, etc.