The fixed ultrahighvolume aerosol sampler serves as the core equipment in automatic radiation environment monitoring stations， and its sampling performance directly affects the reliability of environmental radioactive aerosol monitoring data. Regular calibration of the sampler is essential to ensure the accuracy of monitoring data. This paper proposes a novel online calibration method that acquires the operational parameters of the sampler in real time through a remote data acquisition system and enables intelligent adjustment of the flow calibration coefficient based on an online calibration system. Experimental results show that the flow indication errors at the three test points of the ultra-high-volume aerosol sampler are -2.0%， 1.5%， and 1.6%， respectively， which comply with the technical specifications（±5%） outlined in the “Technical Specification for Operation of Radiation Environmental Air Automatic Monitoring Stations”（HJ 1009—2019）. This method significantly reduces labor and time costs while ensuring the continuity and reliability of monitoring data， providing effective technical support for environmental radiation safety monitoring.