This study investigates the rate-dependent mechanical behavior of thin polyolefin films under uniaxial stretching, focusing on their intrinsic properties and structural modeling for packaging applications. Due to their thinness and high stretchability, accurately characterizing these films remains challenging, particularly in decoupling geometrical effects from intrinsic material behavior. While ASTM D882 and ISO 527-3 standards provide basic mechanical properties, full-field experimental studies are limited due to the complexities of sample preparation and digital image correlation (DIC) setup [1]. In this work, commercial-grade polyolefin-based films were tested, with sample dimensions optimized to minimize stretch-induced localized wrinkling. A full-field 3D DIC system, utilizing an LED white light source positioned behind the film, was employed to enhance contrast in semi-transparent samples. Tensile tests were conducted at three loading speeds (5, 20, and 80 mm/min) to examine rate dependency. The experimental stress-strain response exhibited a distinct Double-Yield (DY) phenomenon and strong viscoplasticity [2]. To capture this behavior, a 2D shell constitutive model was implemented within a finite strain framework, based on an advanced polymer model. The FEM simulation results demonstrated good agreement with experimental data, both globally and locally. This methodology provides valuable insights for the packaging industry, facilitating accurate structural modeling of multilayer films.