The effect of coagulation and annealing conditions on the physical properties of fiber in the on-line dry-jet wet spinning of PAN was investigated. Over the coagulation conditions observed, the crystalline structure was not effected by coagulant composition and coagulation temperature. The degree of crystallinity was nearly independent of coagulant composition, but lowering the coagulation temperature lowered it. The stretchability of as-spun fibers was decreased with increasing the coagulation temperature. The PAN fibers had values of degree of orientation higher than 90% regardless of the coagulation temperature if stretched to a maximum drawing ratio. The density of fiber was increased with increasing draw ratio. The higher coagulation temperature and the higher water content in the coagulation bath were more favorable to produce PAN fiber with better mechanical properties.