The whirlpool structure have been observted in HREM investigation of Si : H films deposited by glow discharge and SiC ultrafine powder synthesized by thermal chemical vapor reaction method. In this structure, strong planes are arranged around its nuclei and this seems to be whirlpools in HREM image. In this article, the cheracters of whirlpool structure are described, its forming reason and the condition under which it can be retained are analysed, and the dependence of it on microcrystal nucleation and growth processes are discussed.