The purpose of this study is to investigate the improvement of fiber surface, physical properties and research the physical properties and dyeability of cotton fabrics treated with KOH solution at low and high temperature. The treatment conditions for mercerization with KOH were changed various temperatures(25, $90^{circ}C$), concentrations(15, 20, 25, 30%. w/v) and times(30, 60, 180, 300sec). The effects of mercerization after KOH treatment estimated with tensile strength, tearing strength, shrinkage, drape stiffness, moisture regain, fiber surface, and dyeability. The optimal conditions were concentration of KOH 20%, time 180sec in low temperature and concentration of KOH 20%, time 60sec in high temperature. The results are as follows; Tensile strength, tearing strength and moisture regain were much improved than those of untreated cotton fabric. Shrinkage and drape stiffness of KOH treated cotton were more increased at $25^{circ}C$ than $90^{circ}C$. Fiber surface showed more rounded shape at $25^{circ}C$ than $90^{circ}C$. Dyeability of cotton fabrics improved by KOH treatment.