When chaotic oscillator changing from chaotic state to large-scale periodic state, its phase diagram symmetry will obviously changed. Hu invariant moment is adopted to describe the different state of chaotic oscillator phase diagram. The threshold value of chaos oscillator under the large-scale periodic state is ascertained by the curve of invariant moment-periodic driving force. According to the difference of Hu invariant moment value for different chaotic oscillatr phase diagram,the state of chaos oscillator can be automatically identified. Finally, the simulated and engineering vibration signals are analyzed, and the results show that invariant moment can accurately identify the state of chaotic os cillator and have better noise-tolerance.