Abstract: The detector quantum efficiency (DQE) is used to describe the propagation of the noise in the imaging system. According to the cascade theory, the DQE of the high-energy gamma camera depends on the gain of the scintillator and the CCD, and the absorbed energy deposition in the scintillator. In this paper, the Monte Carlo code MCNP is employed to simulate the distribution of the energy deposition for X-ray through different scintillators. The DQE of the high-energy gamma camera for different scintillator with different thickness is calculated and analysed. From the simulation, it can be seen that the DQE is correlative with the density and the atomic number of the scintillator. The DQEs of the LuAP and LSO are much bigger than other scintillator with the same thickness. The method presented in this paper can be used to the design of the high-energy gamma camera.