Mechanical and thermal properties of poly(arylene disulfide) synthesized by ring-opening reaction of cyclic(aromatic disulfide) oligomer were reported. These oligomers were prepared from 4,4'-oxybis(benzenethiol). Three-point bending tests were performed to measure the flexural properties of the poly(arylene disulfide). DSC and TGA techniques were used to characterize the thermal properties of these polymers. Ring-opening reactions were carried out by hot-press under atmosphere and nitrogen atmosphere, respectively. Oxidation reaction of these polymers was detected from Raman spectra under atmosphere. The glass transition temperature increased but 10% weight loss temperature decreased with increasing ring-opening temperature. The flexural strength decreased with increasing the temperature of ring-opening polymerization under both atmosphere and nitrogen atmosphere. The polydisulfides could be used as high temperature and thermally curing insulating materials to substitute epoxy resins.