Abstract: Steam explosion was researched to find effects of treatment results on the lumber permeability. The lumber of Mongolian oak and red oak was carried out with steam explosion treatment at the pressure of 0.25, 0.40 and 0.55 MPa. The permeability of treated lumber was measured, compared with that of untreated lumber. It showed that the lumber permeability after steam explosion treatment was higher than that of untreated one, the higher of pressure, and the thinner of the lumber thickness, the greater permeability was.