Vacuum degree online detection of vacuum interrupter has been investigated for more than 50 years.But

there is still no preferable means can be used to practical application. The spectral information of copper material and ambient gas of vacuum interrupter have been studied from 10-3Pa to 105 Pa based on Laser-induced breakdown spectroscopy（LIBS） in laboratory and the change rules of spectral intensities against pressure have been obtained. Furthermore

spectral intensities have been analyzed using principal component analysis（PCA） and artificial neural network（ANN）. The PCA result indicates that LIBS signals under ten different pressures from 10-3Pa to 105 Pa show a good classification. What’s more

the recognition accuracy can reach up to 96.67% using ANN method. A new online detection method of vacuum degree is proposed in this paper which can overcome the poor electromagnetic interference ability

low limit of detection and hard to realize online detection of tradition methods. This method is of great significant to vacuum degree online detection of vacuum interrupter.