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 circuit components in most existing studies, a feasible 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 circuit equations can be simplified to obtain symbolic solutions. Then, an iterative algorithm is constructed for solving operating points. With the aid of the derived expressions, functions of operating point, a parametric analysis of practical behavioral characteristics is also realized. Experimental results demonstrate the effectiveness of the proposed method.