Abstract: The nonlinear dynamics of Superbuck converter is investigated because Superbuck converter is a kind of important topology in the solar photovoltaic power generation system. The discrete mapping model of Superbuck converter is derived by stroboscopic mapping method, based on state equation of the converter. Then the bifurcation diagram of the inductor current is got with the reference voltage as the bifurcation parameter. Finally, the nonlinear dynamics of Superbuck converter is studied by setting up the experimental circuit to verify the whole evolution from stable state to the period-doubling bifurcation state until the chaotic state. On the other hand, ElectroMagnetic Interference (EMI) of the system is effectively reduced through the application of chaos theory by analyzing the power spectra of the inductor current.