In order to study the effect of heat treatment on mechanical properties of polyving akohol (PVA), the command of Build polymers was used to construct 1,3-ethylene glycol polymer chain with 100 monomeric units. The module of Amorphous Cell was applied to put the optimized chain segment into the three dimensional periodic boundary. And the structure model of PVA was obtained. From the temperature 363K to 393K with the increase step of 10K, the molecular simulation was applied to investigate the effect of temperature on mechanical properties in NVT ensemble using COMPASS force field. The cooling rates of 17K/600ps and 5K/600ps were set to simulate the effect of cooling rate on mechanical properties. The results show that mechanical performance of polyving alcohol by slow cooling process is improved; as the rigidity decreases, the elastic elongation and the ductility increase. The mechanical performance of polyving alcohol by heat treatment temperature of 373K is the best, i.e., the Poisson’s ratio and Cauchy pressure are the largest, and the elastic elongation and the ductility are the best.