Intermarriage is a key field in ethnic relations study. A high level of intermarriage only occurs in a multi-ethnic society,where the political system,economic structure,laws,and cultural environment allow young people with different ethnic background to mingle with each other. This is why the intermarriage rate can be used to measure the degree of interaction among different ethnic groups. It is the most reliable indication for the trend of the long-term ethnic relations. Due to the lack of relevant data in official statistics,there are limited studies focusing on intermarriage at the macrolevel. Based on the 1990,2000,and 2010 census data and the special volume on ethnicity edited by the State Commission of Ethnic Affairs,this paper tries to figure out the basic trend of the ethnic intermarriages in China in the past three decades. It discusses some basic characteristics of intermarriages among different ethnicities. To strengthen national unity,ethnic solidarity,and improve the relationship among the ethnic groups is the major challenge faced by China in the 21 st century. The study of intermarriage by sociological and demographic approaches may help understand the basic trend of intermarriages in today’s China.