The Taiwan Power Company's (TPC) coal combustion power plants produced approximately 1 million tons of class F fly ash in 1988 but only 25% of it was effectively utilized. Accordingly, this study investigated the use of separation techniques to improve the quality of the fly ash in order to increase its application. In the experiment, the fly ash was dry-sieved through sieves No. 200, 300 and 400 mesh respectively. The chemical, physical and some of the engineering properties of those classified class F fine fly ashes were ascertained.