Abstract: Due to the impact of parasitic parameters, boost converter has many kinds of distortion waveforms in the output ripple voltage. The traditional analysis results of ripple voltage waveforms ignoring parasitic parameters turns out to be single with large error. Therefore, it is necessary to further study and reveals the distortion mechanism of ripple voltage and establishes a more accurate mathematical model. It is found through research that the equivalent series resistance（ESR） of the output filter capacitor is the main cause of the distortion of the output ripple voltage waveform and the large error. Considering the problems that exist in the traditional method of analyzing the output ripple voltage of boost converter which ignores ESR, a method of modeling the ripple voltage considering the filter capacitor ESR was proposed. As is the findings show, there are five kinds of ripple voltage waveforms in the continuous conduction mode（CCM） and discontinuous conduction mode（DCM） of inductor current, and the analytical expressions of each type of output ripple voltage in different modes were derived. On this basis, the experimental results verified the correctness of the analysis of ripple voltage distortion mechanism, and showed that the mathematical model of ripple voltage has higher precision.