A complete set of simple and easy simulation facility has been designed under condition in the laboratory.Through changing the environmental parameters

i.e.temperature and pressure

the influence of ambient air pressure upon separating out behavior of the water content in coal has been investigated.Results of study show that as in the following:(1)under condition of constant ambient temperature

decrease of ambient air pressure i.e.increase of ambient vacuum

to below the saturation pressure of water content under said temperature

the separating out rate of water content increases as the difference value between them increases;(2)under condition of constant air pressure

increase of ambient temperature to above the saturation temperature of water content under said air pressure

the separating out rate of water content increases as the difference value between them increses.The separating out rate of water content in coal is affected by the concentration of ambient water vapour

under condition of constant pressure

maintaining the flow energy of ambient air and timely carry away the water vapour from surface of coal

it is favourable to separate out the water content in ocal.