Abstract Ambient dose equivalent dosemeters are widely distributed in nuclear facilities for routine continuous monitoring or nuclear accident emergency monitoring, they are inconvenient to be disassembled and sent to the metrology laboratory for calibration. To ensure the accuracy of such dosemeters, the research of in-situ calibration method has been carried out. Ambient dose equivalent secondary standard ionization chamber and portable gamma ray irradiation facility have been designed for in-situ calibration. The experiments of in-situ calibration were carried out in five typical sites located in China Institute of Atomic Energy, results showed that the relative deviation between in-situ calibration factors and metrology laboratory calibration factors are within 5%.The combined standard uncertainty of the in-situ calibration factor is 2.8%, and the expanded uncertainty is 5.6% (k=2).The in-situ calibration method can meet the calibration requirements of the fixed ambient dose equivalent dosemeters.