To improve the drying rate and drying quality of Samanea saman Merr., the wood samples were pretreated under the conditions of ultrasonic frequency of 25 kHz, power of 340 W, and time of 30, 60, and 90 minutes. The effects of ultrasonic pretreatment on relative crystallinity, drying rate and dimensional stability of Samanea saman Merr. were explored. The results showed that drying speed and dimensional stability were improved along with the increasing pretreatment time; the ultrasonic pretreatment increased its relative crystallinity. Considering the drying rate and energy consumption, the optimal ultrasonic pretreatment time of Samanea saman Merr. under this test condition was 60 minutes.