Firstly studied the deep trap state of typical polymeric material using optical parametric oscillator (OPO) as an exciting source by the method of photo-stimulated discharge (PSD). The wavelength of output laser is tunable continuously in the range of 210-420 nm and the mean energy of photo-impulse which has a width of 3-5 ns is about 2.3 mJ. The experimental results show that this laser source can be well implemented in the PSD measurement. For example,the activation energy of the polyethylene terephthalate (PET) is 4.27 eV and the activation energy exists on polypropylene (PP) is 4.92 eV and 5.17 eV which all belong to the deep trap. The activation energy is the essential parameter to characterize the polymeric dielectric material which can provide fundamental data and scientific reference for the improvement to enhance the electric properties of the material.