The voltage-controlled Buck converter is a typical nonlinear circuit system. According to the working characteristics of the DC-DC Buck converter, a simulation model for studying its nonlinear phenomena is established. The bifurcation stability and chaos of the Buck converter are analyzed. The chaotic phenomenon and system output characteristics are revealed by taking input voltage and inductance as bifurcation parameters. The influence of the intersection point of reference voltage waveform and output voltage waveform on the operating state of the converter is analyzed from the perspective of time domain. The evolution process of the system from stability to chaos is obtained in the phase diagram. The rationality and feasibility of the model are verified. The research method also provides theoretical and experimental basis for the bifurcation and chaos of converters with other modes of DC-DC.