Abstract: The paper introduces a method and principle for calibrating energy response of γ-ray detector. The energy response may be obtained by means of transforming γ-ray from 60Co into a series of mono-energetic γ-ray in the range of 0.36～1.02 MeV， shielding radiation－interference and improving energy resolution. The energy distributions of scattered γ－ray at different angles and corresponding energy deposited in detector were simulated by MCNP code. The results show that the signal－to－noise of the system is about 20∶1， the energy resolution is about 6%，and the sensitivity of detector to 0.66 MeV γ－ray is in agreement with the one to the γ－ray from 137Cs.