Eucalyptus grandis×E. urophylla wood samples were pretreated by ultrasound at 340 W power with frequency of 25 and 59 k Hz for 30, 60 and 90 minutes, respectively, and the effects of ultrasound pretreatment on drying time of the eucalyptus wood samples were investigated. Results indicated that ultrasound pretreatment could decrease drying time and increase water diffusivity of the wood samples.Moreover, drying rates and water diffusivity increased along with increase of ultrasound frequency and pretreatment time. The effect of ultrasound pretreatment on shortening drying time was very obvious when wood moisture content of the samples was above fiber saturation point.