The invention provides a device used for adjusting air flow humidity of an airborne particulate concentration monitoring instrument, which is mainly used for detecting various particulate matters in an atmospheric research. The device consists of a tubular structure (1), a hygrometer (2) with a humidity probe, a humidification channel (3), a drying channel (4), a put-through channel (5), a computer (6) and a power supply (7), wherein both the hygrometer (2) with the humidity probe and the computer (6) are connected with the power supply (7). The humidity of collected air flow is detected, anda sample entering the airborne particulate concentration monitoring instrument is kept within a reasonable humidity range by a humidifying or drying means, so that the monitoring result of the airborne particulate concentration monitoring instrument is more real and more reliable.