CdS solid thin filmswere prepared on the substrates of slide glass or ITO coated glass by using chemicalpyrolysis deposition technique(CPD) at different deposition temperature from 350 to 540℃ during film growth. Some of theprepared CdS films were undergone thermal annealing treatments at temperature from 200 to600℃. Themicrostructures of as-deposited CdS films before and after thermal annealing wereinvestigated with SEM, AFM and XRD measurements.It is found that hexagonal structure-likephase can be obtained for CdS films prepared with CPD when the deposition temperature isbelow 540℃. Wurtzitephase appears when CdS films are prepared at deposition temperature higher than 540℃, or the CdS films are preparedwith CPD at deposition temperature of 400℃ and post-annealed at the temperature above 500℃. The grain size of CdS films, which is dependent ondeposition temperature and on different substrates, is also discussed.