The invention belongs to the technical field of
dust detection, and discloses a
system for calibrating particulate matter measuring instruments and a calibrating method of the
system. The
system comprises a
compressed air processing device, a dust generator and an evenly-mixing box, wherein the
compressed air processing device, the dust generator and the evenly-mixing box are sequentially communicated. A dust sample collector and a dust removal device are communicated with the lower portion of the evenly-mixing box. The evenly-mixing box comprises a
sedimentation mixing chamber, a mixing section and a sample discharging section. The mixing section comprises a dust feeding
pipe, a mixer and an upper transition cavity, an air diluting bin is formed between the dust feeding
pipe and the mixer, a plurality of
compressed air inlets are evenly formed in the portion, corresponding to the air diluting bin, of the dust feeding
pipe in a communicated mode, and mixing through holes for diluting air in a non-directional mode are evenly formed in the pipe wall of the mixer. By means of the system and the calibrating method, the dust generation amount, the
dilution air flow, the dust
dilution concentration, the sample flow and the evenness of mixing of dust and
dilution air are all effectively controlled, and therefore measuring instruments within different dust
mass concentration ranges can be calibrated.