A zone-drawing and zone-annealing treatment was applied to poly(p-phenylene sulfide) fibers in order to improve their mechanical properties. The zone-drawing (ZD) was carried out at a drawing temperature of 90 degrees C under an applied tension of 5.5 MPa, and the zone-annealing (ZA) was carried out at an annealing temperature of 220 degrees C under 138.0 MPa. The differential scanning calorimetry (DSC) thermogram of the ZD fiber had a broad exothermic transition (T-c = 110 degrees C) attributed to cold-crystallization and a melting endotherm peaking at 286 degrees C. The T-c of the ZD fiber was lower than that (T-c = 128 degrees C) of the undrawn fiber. In the temperature dependence of storage modulus (E＇) for the ZD fiber, the E＇ values decreased with increasing temperature, but increased slightly in the temperature range of 90-100 degrees C, and decreased again. The slight increase in E＇ was attributable to the additional increase in the crosslink density of the network, which was caused by strain-induced crystallization during measurement. The resulting ZA fiber had a draw ratio of 6.0, a degree of crystallinity of 38%, a tensile modulus of 8 GPa, and a tensile strength of 0.7 GPa.