In this paper, we propose a modeling based scheme to study the practical characteristics of Buck zero-voltage switching quasi-resonant converters (Buck ZVS-QRC's). Instead of assuming the unity power efficiency and/or having the ideal characteristics of all the circuit components in the most existing studies, a novel model taking the equivalent intrinsic resistance of each circuit component and the voltages of inductors into account is used to describe the steady-state operation of the converter. By using the developed technique, the governing equations of converter can be simplified. An iterative algorithm is then constructed for solving operating points. With the aid of the derived expressions for the circuit operating point, a parametric analysis of practical behavioral characteristics is also realized. Experimental study of a practical converter demonstrates the effectiveness of the proposed method.