<p>Passive daytime radiative cooling materials with simultaneous high solar reflectance and infrared thermal emittance, hold enormous potential for addressing the energy crisis and global warming through advantages of zero energy consumption and low carbon emissions. Herein, novel hierarchically porous nanocomposite films with randomly distributed heterogeneous pores and nanoparticles are fabricated in a low-cost and simple method known as non-solvent-induced phase separation method with two solvents and water, employing polyvinylidene fluoride (PVDF) (10%) and zinc oxide (ZnO) (90 nm, 2%) nanoparticles. Utilizing the regulation of structural parameters such as pore size and film thickness (200-600 μm) to control multi-scattering of light by the films,hence cooling performance is achieved. The porous structure of the films was evaluated by SEM analysis as well as cooling performances were measured by a hotplate apparatus combined with a halogen lamb as a sun simulator. SEM images show that the most obvious heterogeneous pore structure was obtained in the samples with a film thickness of 400 μm. However, it has been determined that as the film thickness increases, there are macro and nano-micro heterogeneous pores in the film structure, but the number and size of macro pores decrease. The trend regarding pore formation, size and number of pores was also detected in the cross-sectional images of the films. Under exposure to a solar intensity of 600 Wm−2, compared to non-porous PVDF films, an effective passive cooling effect was achieved due to a higher temperature drop in porous PVDF films in the range of 2.14-5.6°C. The porous nanocomposite films lower the temperature effectively especially at a film thickness of 600 μm by an average of 6.5°C. This work opens up a simple, cost-effective, and scalable route for achieving efficient radiative cooling nanocomposite films with excellent cooling performance based on multi-scattering effect with controllable porous structure and ZnO.</p>