Abstract In order to study the effect of pressure on the water absorption capability of coal, the water injection experiments of two coal samples were done under different pressure source conditions and room temperature by using self-designed pressurized water device. The experimental results show that pressure has a positive effect on water absorbability; water absorbability gets large as the pressure increases; the earlier water absorbability of coal is rapid, and the water absorbability of coal displays a similar Langmuir-isothermal adsorption curve with the changes of time, and it has saturated water absorbability. The water injection pressure is higher, which not only strengthened the ability of expanding seepage space, but also developed the transporting water and storage water space. The later water absorption curve of coal becomes weaker, and water adsorption process is mainly influenced by capillary force. The pressure water only supplies provisions and time is the main influential factor.