A polymeric blend nanocomposites were prepared using mixer of Epoxy and polysulfide rubber [EP+PSR] as a matrix material and the Zirconium Oxide Nano-powder ZrO2 as a reinforcement material, in different particle sizes and same adding ratio of 2% wt . Hand Lay-up molding method was used to prepare the samples. Impact strength, compression resistance and thermal conductivity tests, were carried out for the polymeric blend and composites samples before and after immersion in tap water. The results showed that adding Nano zirconia powder to the polymer blend improved the mechanical properties, while the thermal conductivity of the polymer blend was higher than that of the composites. Also, it was observed that water immersion caused a decrease in impact strength, compression resistance, modulus of elasticity and thermal conductivity in a manner proportional to the immersion time.