In this paper, the chaos dynamics behavior of a third-order nonautonomous ferroresonance chaotic circuit with single phase transformer has been analyzed and simulated. We drew the conclusion that there is only a nonlinear flux-controlled inductance in this circuit, which has been investigated and simulated by using a fourth-order autonomy improved system. We confirm that the chaotic behavior exists in this circuit by computer simulation and circuit experiment. A simple method of controlling chaos is proposed by varying the linear capacitance parameters.