This article demonstrates that the Cultural Revolution led to a temporary decline in educational homogamy in urban China, which was reversed when the Cultural Revolution ended. Previous studies on educational homogamy in China have paid incomplete attention to China’s shifting institutional structures. This research applies institutional theory to the trend of educational homogamy in urban China. During the Cultural Revolution (1966–76) state policies lowered educational legitimacy, educational homogeneity and mating opportunities in school in the urban marriage market while enhancing them before and after. From the institutional perspective I hypothesize that the strength of educational homogamy in urban China during the Cultural Revolution was weaker than before and after. I use log-multiplicative layer effect models to analyze data representative of urban residents in 20 cities. I find moderate but significant evidence for the institutional hypotheses. Educational assortative mating is subject to political intervention in urban China.