Abstract: In our paper, bulblets in vitro of oriental lily cv. ‘Siberia’ was used as materials to study effect of root length and diameter of bulblet and transplanting substrates on transplanting results. The results showed that A₂ substrate (imported turf∶vermiculite∶pearlite=7∶1∶2) was the best one to acclimatize and transplant the bulblets, showing significantly higher transplanting survival rate, fresh weight and girth of bulblet than that ones in other substrates. When root primordium was under 1.5 cm, transplanting survival rate was higher. When root length was over 3.0 cm, transplanting survival rate was lower. The higher the bulblet diameter was, the higher transplanting survival rate, bolting rate and bulblet girth were. When bulblet diameter reached over 1.5 cm, both transplanting survival rate and bolting rate were highest.