In the preparation process of polytetrafluoroethylene (PTFE) turning film, cloud spots may appear due to the different morphology, particle size and molecular weight of PTFE raw materials, resulting in poor uniformity of crystallinity, density and light transmittance. Two kinds of PTFE turning films with cloud spot defects were heat treated. Through density test, it is found that the density uniformity is improved after heat treatment. The crystallinity was characterized by differential scanning calorimetry (DSC). The results show that the difference of crystallinity decreases from 2.22% and 12.79% to 0.38% and 0.47% respectively after heat treatment, which is almost negligible. The transmittance was characterized by ultraviolet-visible spectrophotometer (UV-vis) spectrophotometer, and the results show that the difference of transmittance decreases from 18.04% and 8.28% to 0.54% and 1.08% respectively, and the uniformity of the cloud spot films is obviously improved.