Raman spectroscopy is a powerful tool to judge the fundamental building units contained in crystal structure. In this work, it was used to investigate the basic structural groups involved in the low temperature (LT) and high temperature (HT) phase YBO3. The characteristic Raman vibrational bands of the LT and HT phases YBO3 were identified respectively. The characteristic vibrational peaks of the LT phase YBO3 locate around 410 cm(-1) and 500 cm(-1), both of them are attributed to the ring bending modes of B3O9 group. The strong characteristic vibrational band of the HT phase YBO3, arising from the symmetric stretching mode of BO3 group, locates around 940 cm(-1). A structural phase transition with a large thermal hysteresis was found. During the phase transition process, the B-O bonds of the BO4 groups break and the B3O9 rings cleave into the BO3 plane conjugated groups. (C) 2011 Elsevier B.V. All rights reserved.