Different temperatures of superheated steam were used to pre-treat boxed-heart larch lumber.A series of radio frequency vacuum drying tests were then conducted on the pretreated lumber.The results showed that the number and the total length of surface checks decreased considerably in the samples pretreated under 105 ℃ atmospheric superheated steam for 31 hours.We also observed that the final moisture content distribution was more uniform with the pretreatment.Based on the drying cycle and drying quality,we concluded that the superheated steam pretreatment was feasible for mills even though it required a longer drying cycle.