By introducing institutional environment and human capital into the“cost discovery”model, we explore the micro impact mechanism of institutional environment and human capital on the quality improvement of export products through enterprise innovation and imitation choice, and measure the impact effect by using the cross-border panel data of 145 economies from 1996 to 2014. The results show that: the multi-dimensional institutional environment measured by political stability, government effectiveness, regulatory quality, rule of law, and control of corruption has a significant positive correlation with the quality of export products, while the impact of human capital on the quality of export products presents a U shape, but it shows heterogeneity in countries with different income levels. Human capital plays a moderating role in the process of the impact of institutional environment on the quality improvement of export products. Economies with higher level of human capital have the smaller effect of their institutional environment on the quality improvement of export products; on the contraty, the institutional environment of an economy with a lower level of human capital plays a greater role in improving the quality of exports products. This is related to the diminishing marginal impact of institutional environment and the threshold role of human capital, which shows that improving institutional environment is more meaningful in low-income countries, and improving human capital is more critical in high-income countries.