Abstract:The visibility meter calibration system is the standard equipment for visibility calibrating, and its uncertainty directly affects the calibration results of forward scattering visibility meter. In this article, the structure, specification and calibration method of the visibility meter calibration system of the national visibility meter calibration laboratory are introduced, the main uncertainty source of the calibration process is analyzed, according to the National Calibration Specification of JJF 10591-2012 Evaluation and Expression of Uncertainty in Measurement, Type A and Type B uncertainty of the calibration system are evaluated using the visibility data, meanwhile, three forward scatter visibility meters are calibrated using the calibration system. Results show that the uncertainty of the system below 3000 m visibility is 58%, after calibration, the biggest and smallest relative errors of three forward scatter visibility meters at 100,500,1 000,1 500,2 000,3 000 m are 78% and 18% respectively, which can meet the visibility meter calibration and operational measuring requirements.