By investigating the deep-rooted gender norms and social-cultural factors， this paper explores whether and how traditional gender role attitudes impact on income gaps between men and women， and identifies causal effects by methods of instrumental variables estimation and other causal inference methods. Using the 2013 Chinese General Social Survey data， the results show that traditional gender role attitudes are detrimental to the earnings of women， but has no direct effect on men’s income. Through Oaxaca-Blinder decomposition， this research finds that the different effects of gender role attitudes on income of men and women appear to play a prominent role in causing the gender gap in earnings. In addition， gender role attitudes have an indirect and wide effect on gender income inequality through educational investment， labor participation， working hours and occupational status. This provides a new perspective for understanding the persistence and mechanisms of gender income stratification under the trend of educational equalization， and has implications for gender equality policies.