In this work,we used real-time measurement to investigate the I-V characteristic of extended wavelength InGaAs infrared detectors under 55×104 rad γ irradiation.The results indicate that the dark current of the devices have no obvious change,the R0 have small changes.The detector performances were measured before and after irradiation,the results show that the signal of detector decrease slightly after irradiation,and the noise almost don′t change,which means the detect performance becomes a little worse after irradiation.The low frequency noise was also measured,the results show that the noise in the low frequency region have no noticeable change.These results imply that to the extended wavelength InGaAs infrared detectors the γ irradiation has little effect.