Depolarization pump structure of Erbium Doped Fiber Source(EDFS) is designed to solve the problem that polarization state of pump influences high precision EDFS average wavelength stability for Fiber Optic Gyroscope (FOG). This structure is adopted to Lyot depolarizer to depolarize pump light, and the Lyot depolarizer parameters selection is analyzed theoretically in the design construction. Experimental results prove that the polarization property of Wavelength Division Multiplex (WDM) affects the EDFS average wavelength stability, and the design structure can effectively reduce polarization property of WDM. When EDFS parameters have been optimized, considering that the pump of polarization state influence EDFS average wavelength stability, measure EDFS in the temperature cabinet. Experimental results show that without control polarization state, EDFS average wavelength stability is 77 ppm, while, adopting the structure of pump light complete depolarization, EDFS average wavelength stability is enhanced to 4 ppm.