Abstract: In view of the difficulties of uncertainty and traceability in the measurement of ambient air particle concentration, and in close combination with the requirements of national standards and Metrological Development Plans for measurement and traceability of aerosol particle mass concentration, the key technologies such as particle sampling, particle size separation and particle mass concentration measurement are focused on, and the metrological traceability system for ambient air particles has been established through scientific and technological research, which is carried out systematically on national reference materials, measurement standard devices, international equivalence of technologies and national standards. The project research ensures the accuracy and reliability of the monitoring data of ambient air particles, the consistency with international monitoring data and the traceability standard’s establishment in the field in China.