Parametric oscillations occurred in a nonlinear two-phase circuit with nonlinear reactors and capacitors are applied to many kinds of power devices. When the devices are operating under light loading, the output voltage of these devices shows unstable oscillations: subharmonic oscillations, quasi-periodic oscillations or chaotic oscillations. This paper deals with an analysis of the abnormal oscillations and verify the validity of the analysis experimentally. In this paper, the authors offer new circuit equations that can be applied to the analysis of two-phase. nonlinear circuit in which reactor saturation curves are sharp. It is clarified by this analysis that the parametric oscillations of the circuit which contains reactors of moderate saturation characteristics become subharmonic or quasi-periodic oscillations with the existence of resistances of the power supply side; and when the nonlinearity of the reactors in the circuit is sharp, the parametric oscillations may change into chaotic oscillations besides the aforesaid oscillations.