In this research work, steady state analysis of quasi-resonant zero current switching (QRZCS) boost converter is investigated using state-plane diagram approach. Expected waveforms of inductor current and capacitor voltage can be mathematically obtained from this approach. For the circuit design purposed, the control frequency characteristics can be derived from the analysis. This paper shows that the use of state-plane diagram for analyzing the resonant converter is easy to understand. However, the computer simulation of the proposed converter is also done to confirm the analysis.