<p>Dielectric polymers play a crucial role in various applications, including energy storage, flexible sensors, and actuators. The thickness of commonly used polymer films is often on the micrometer scale. This study aims to demonstrate that the impact of surface layer effects on material properties is significant and should not be overlooked in thin dielectric films. Specifically, we investigated the dielectric and piezoelectric characteristics of ferroelectric polymer poly(vinylidene fluoride-ran-trifluoroethylene) (P(VDF-TrFE)) films of varying thicknesses. Our findings indicate that as the thicknesses of the P(VDF-TrFE) films increase, both the dielectric and piezoelectric properties are enhanced. Furthermore, in linear dielectrics, such as polyetherimide (PEI), there is also a correlation between the dielectric constant and film thickness. We employed a three-layer capacitor model to fit the variation in dielectric constant with thickness and the fitting result suggests that the dielectric constant of the surface layer of polymer films is lower than that of the bulk phase.</p>