Long-period fiber grating (LPFG) written by high frequency CO₂ laser pulses in panda polarization maintaining fiber was proposed,and its polarization characteristic was generally studied by experiments. The experiment results show that the resonant amplitude of LPFG changes periodically with a period of π when the polarization angle of incident elliptical polarization light varies from 0 to 2π. The amplitude change directions of two adjacent resonants were opposite with a phase difference of π and the amplitude difference of them in the same incident polarization angle varied periodically as a zigzag wave also with a period of π. The resonant wavelengths of LPFG hardly varied when there was no mode disturbs.Based on mode couple theory,the experiment results were explained qualitatively in this paper.