Equal pay is an essential component of gender equality, one of the Sustainable Development Goals of the United Nations. Using data from over ten million Chinese online job seekers, we find that women earn only 71.57% of men’s salaries, with a persistent gender pay gap across all age groups and education levels. Despite progress in education, the economy, and culture, China’s gender pay gap persists, suggesting that traditional policy approaches focused on improving women’s human capital have reached their limits. Our analysis indicates that 81.47% of the pay gap may be due to discrimination, especially for married women. Taken together, we suggest that more research attention should be paid to the effect of discrimination in understanding the gender pay gap based on the family constraint theory. We also suggest the Chinese government increase investment in family-supportive policies and grants in addition to female education.