Abstract: Three kinds of man-made radioactive sources were chosen and experimental calibration for source-searching mode was done using existing advanced mass airborne γ-ray spectrometer based on technical standards of airborne radiation survey from IAEA and industrial experience of home and abroad. Experimental calibration method and plan in point source mode using airborne γ-ray spectrometer were introduced. In the process of the experiment, experiment condition and process quality were strictly controlled and calibration parameters of ²⁴¹Am, ¹³⁷Cs and ⁶⁰Co were obtained. Calibration parameters of other nuclides can be estimated according to those of ²⁴¹Am, ¹³⁷Cs and ⁶⁰Co and the airborne survey system is able to search manmade radioactive sources and perform qualitative measurement by this way.