Abstract: Based on BEGe γ spectrometer, the scanning measurement was operated by parallel 59.54 keV γ-ray which was emitted by ²⁴¹Am. The crystal diameter was obtained by scanning perpendicular crystal front surface, and the crystal height was obtained by scanning perpendicular crystal lateral surface. The crystal parameters provided by manufacture and scanning were used to establish the Monte Carlo module. Based on the calibration results of the sources, the front and lateral dead layer thinknesses of BEGe were characterized. A good consistent result between Monte Carlo result and experiment value was finished by using character parameters, and the best theory module was obtained. Viewing the result data, the parameters are valid and reliable. The Monte Carlo results are consistent with the experimental results of point source in 2%. Therefore, this method greatly improves the γ spectrum’s metrical accuracy, and it can be widely applied in detector efficiency calibration and environmental radioactive investigation.