Abstract: The microstructure of CdI2 thin film grown during vapor-phase deposition was investigated by scanning electron microscopy (SEM). The thin film deposited on Si crystal consists of numerous sunflower-like aggregates. These aggregates display well self-assembly characteristics. The size of Sunflower-like aggregates is between 12 and 44 μm. Each sunflower-like aggregate is surrounded with many adjacent wings-"petals". The structure of central region of the "sunflower" is obviously difFerent from that of the "petal". Electron spectroscopy for chemical analysis (ESCA) was employed in determining the chemical valence of the thin film. Self-organization efFect is used to explain the coring growth process of CdI2 thin film