In this paper, annealing processes for stress relaxation and removing residual stresses from polycarbonate sheet are studied and evaluated using experimental tests. Then, by making some alterations and modifications in the previous heating cycles thermal operations are performed on different samples in a try and error process. Appraising the obtained results, a modified thermal cycle is presented which can remove the residual stress from the polycarbonate sample, while reducing the time and cost of the annealing process. According to this process, the temperature is raised to 100˚C at the heating rate of 20˚C/h. The samples are kept at this temperature for 3 hours and then, the heating is continued up to 140˚C at a slower rate of 5˚C/h. Then, the specimens are heated at the rate of 1˚C/h until maximum temperature of Tmax = 156˚C. After reaching this point, the samples are cooled immediately, and the cooling rates are same as the heating rates.