In the past century, China has undergone rapid and dramatic social and economic changes. This article describes trends in educational assortative marriages of cohorts born in 1906–1995 in China. We measure educational attainment relatively as an individual's percentile position in the education distribution of a 10-year birth cohort and study trends using comparable, easy-to-interpret couple rank-rank correlations. We analyze microdata samples from the 1982, 1990, 2000, and 2010 China censuses and the 2015 1% intercensus survey and nationally representative surveys between 1996 and 2018. We find a large and steady increase in educational assortative marriage over the past century, except among those born in 1946–1965, whose schooling and marriage were impacted by the Cultural Revolution. Our study highlights the critical roles of social, political, and economic contexts in shaping trends in educational assortative marriage.