We present a method of anti-control of chaos on the degenerate optical parametric oscillator via modulating the reduced decay rate of the fundamental mode with a sinusoid wave to convert the steady state without output of subharmonical mode or periodic state into chaotic state. Numerical simulation shows that there are different chaotic orbits corresponding to different modulation amplitude and modulating angular frequency only if the maximum Lyapunov exponent of the system is positive. The maximum Lyapunov exponent as a function of modulation amplitude and modulating angular frequency is calculated respectively. We point out here that converting the steady state without output of subharmonical mode into chaotic state is more difficult than converting the periodic state into chaotic state because narrower range of modulation amplitude and modulating angular frequency can be used in the former case.