Abstract: A large number of radiation dosimeter are needed in nuclear power plant to ensure the safety of personnel and environment. Reference radiation is a necessary condition for the calibration of radiation dosimeter. Due to the large number of radiation dosimeters used in nuclear power plant, gamma calibration laboratory is usually built for the calibration of radiation dosimeter in nuclear power plant. The optimal design of ⁶⁰Co single source irradiation facility and ¹³⁷Cs multi-source irradiation facility was completed by Monte Carlo method. The scattering ratio and uniformity of radiation field were measured by PTW cavity ionization chamber. The results show that the technical parameters of gamma calibration laboratory meet the requirements of ISO4037 standard, and the equipment can be used to carry out the calibration and verification of radiation dosimetes in nuclear power plant after the standard evaluation.