Abstract: Based on numerous studies of γ detector calibration in laboratory and actual situation at China Experimental Fast Reactor (CEFR), a set of special calibration device which is suitable to calibrate fixed γ detector at CEFR was designed and manufactured, and the substitution method was used for the calibration of CEFR fixed γ detector. The results show that the special calibration device and the calibration technology satisfy the requirement of CEFR fixed γ detector on-site calibration.