In order to solve the calibration problem of air negative ion measuring instruments, based on the working principle of air negative ion monitor, a method for tracing the source values of instruments and a method of developing the calibration equipment are proposed. The developed negative ion generator and standard negative anion measuring instrument are tested and verified. The verification results show that the anion field produced by the anion generator has the characteristics of continuously adjustable anion concentration, good stability, fast response speed and small particle size, the relative error of the standard negative ion measuring instrument is not more than ± 5%, and the measurement uncertainty of the standard device is 6%, which can be used for the calibration and test of the negative ion measuring instrument. Using a calibration device composed of the negative ion generating device and the standard ion measuring instrument, a calibration test is performed on two different negative ion measuring instruments, and the measurement errors are analyzed to verify the scientific rationality and feasibility of the calibration method.