In this communication, we demonstrate a new approach to well-controlled growth of Se nanowires and nanotubes, which comprises a hydrothermal process and a following sonication. The hydrothermal process was used to derive Se particles of trigonal phase. In the subsequent sonication, if the Se particles were large enough, they were first broken, and then aggregated along the circumferential edge of the gap thus forming Se nanotubes; conversely, the Se particles were not broken and then aligned into nanowires. The high-resolution transmission electron microscopy (HRTEM) proved that both the Se nanotubes and nanowires were single crystalline in nature and <100> oriented. Based on a series of the TEM observation, a phenomenological mechanism for the elucidation of the controllable growth of Se nanowires and nanotubes is presented.