Marriage is declining in China. Among singles, the probability to marry in 2019 was twice as low as in 1999. We estimate a Choo and Siow (2006b) model using census data to quantify the relative roles of changes in population structure and changes in marital surplus, i.e., value of marriage. We find that the increase in the supply of educated people explains half of the decline, partly due to a mismatch between educated women and less-educated men. The deterioration of female-to-male ratio, known as the marriage squeeze, explains an additional 18% for men. The decrease in surplus explains the rest.