Abstract: In order to investigate the influence of chalk ash on the air aerosol concentration in the classroom environment,the chalk aerosol of a regular classroom in a university was monitored by Fidas-100 ultrafine particle aerosol particle size spectrometer.The distribution of aerosol concentration over time at different locations on the blackboard was measured.The experiment results indicated that the PM10 aerosol connection increased by nearly 13 times after wiping the blackboard.The proportion of respirable particles PM10 contained in chalk aerosols is large,which has an important impact on indoor air pollution.The farther away from the blackboard,the lower the peak concentration of the chalk aerosol and the longer the concentration takes to reach the peak value.