Unlike most existing studies on the endogenous institutions, literature on theoretical growth has traditionally considered institutions as exogenous. In this paper, a learn-by-doing-based growth model is adopted and integrated with endogenous institutions to study how economic agents’ incentives engage in institutional improvements or exploit institutional imperfections. From maximization of identical agent utility, the economic growth model includes capital, labor, technology, and institutions. The study is to analyze the effect of institutions on the stability of equilibrium, balanced economic growth path, and convergence rate in the process of economic growth. It is concluded that, firstly, improving institutions is a decisive factor for China’s high economic growth rate for the past years; secondly, improving institutions can increase the capital stock per unit of effective labor in steady state; thirdly, imperfect institutions can explain income difference among countries; and finally, technology plays a key role only under the conditions adapting to institutions.