Polyester fibers can be modified into cationic dyeable polyester fibers(CDP) by the copolymerization of terephthalic acid and 5-sodium sulphoisophthalic acid with ethylene glycol. The advantage of CDP on most cationic dyes is the conspicuous brilliance due to a narrow steep absorption band and the wash fastness and etc. Weight reduction by alkali hydrolysis, dyeing and solvent wicking properties of fabrics with cationic dyes, and change of fine structure were investigated. To obtain optimum splitting process parameters for dyeing and physical properties of micro CDP fiber, splitting method under various conditions was carried out. By means of SEM, it was confirmed that the splitting process of the micro CDP fiber be achieved at the weight reduction. A comparatively greater quantity of dye is necessary to dye microfiber than conventional fiber. The fastness and solvent wicking of regular CDP fiber is higher than that of micro CDP fiber.