The comparative advantage of factor endowment not only depends on factor gross but also is affected by factor structure, as a result, the change of factor structure produces the influence on export structure. The analysis based on the three-stage iterative model shows that population age structure not only affects labor supply gross but also influences production structure and capital stock through the change of inhabitants’ consumption (savings) behavior, furthermore, affects export product structure. Specific expression is that the increase of aging and fewer children can boost the change of export comparative advantage and export product structure towards capital-intensive products. The empirical analysis based on 140 countries and regions during 2003—2015 shows that there is positive correlation between elderly dependency ratio and capital-intensive product export, that there is negative correlation between children dependency ratio and capital-intensive product export, and that with the increase of aging and fewer children, the marginal influence of elderly dependency ratio and children dependency ratio on export product structure gradually becomes smaller. China should conform with the change trend of population age structure, change trade development ways and realize the transformation and upgrading of trade structure.