Abstract: To promote the continuous improvement of ambient air quality in China,the coverage of PM_2.5 monitoring network is continuously expanding,and the requirements for the accuracy of monitoring data are increasing stringent.To obtain high-quality monitoring data,the traceability requirements for PM_2.5 measuring instruments have significantly increased in both scope and precision.However,traditional laboratory calibration methods can no longer meet existing needs,so it is urgent to develop new in-situ field calibration technology to improve the accuracy and convenience of PM_2.5 measuring instrument calibration.The project takes the development of portable low concentration PM_2.5 generator as the core,breaking through the technical bottleneck of traditional small particle generator in applications with mass concentration below <1 mg/m³.By integrating this generator with other auxiliary measuring equipment,a new in-situ field calibration technology for PM_2.5 measuring instruments was constructed.The experimental results show that the mass concentration stability of PM_2.5 produced by this technology is below 2.6%,the export consistency difference is below 3.4%,and the uniformity is below 3.8%,fully meeting the requirements of PM_2.5 measuring instrument calibration specifications.Compared with traditional technologies,the calibration results of this technology are consistent,which proves its reliability and effectiveness.Furthermore,experimental validation indicates that this technology can also be applied to the field calibration of low-concentration dust meters (1-10 mg/m³).The in-situ field calibration technology developed in this study provides innovative metrological support for the field calibration of PM_2.5 measuring instruments and low-concentration dust meters,and effectively promotes the in-depth development of environmental monitoring technology.