High temperature Raman spectroscopy has been used to probe the growth units existing in PbMoO4 melt. According to the Raman spectra of PbMoO4 crystal at various temperatures and the melt just above the crystal melting point, we found that Pb2+ cations and ［MoO4］2－ groups acting as the growth units exist in the melt. Further, we have studied the interaction between the growth units and various low-index planes of PbMoO4 crystal. The crystal growth habit and the cause of dendrite growth are explained. Finally, we point out that the best seed orientations for the crystal growth are parallel to its 101 planes.