In order to solve the endogeneity between democracy and trade, this paper included the relationship between democracy and factor endowment into the regression equation, and carried out simple least squares regression respectively on the two models with democracy as an important variable and control variable. The regression results show that democracy promotes trade, but the interpretation degree of democracy to trade is relatively low. Only when the control variables are included, the variables have a more obvious interpretation effect on trade. The relationship between democracy and factor endowment will affect the promotion effect of democracy on trade. In order to avoid the inaccuracy of regression results caused by the mutual influence of democracy on import and export trade, this paper discusses the influence of democracy on import and export separately.