The work aims to prepare an environment-friendly and highly transparent anti-fogging coating to address the easily fogging problem in plastic packaging films for fresh products. Polyvinyl alcohol (PVA) and sodium alginate (SA) were used to prepare the anti-fogging coating which was coated on the surface of polyethylene (PE) film via blade coating. The composition of the coating and its effect on the anti-fogging performance of the film were tested and analyzed, and the motion behavior of water molecules at different interfaces was analyzed by molecular dynamics simulation software to explore the anti-fogging mechanism of the PVA-SA coating. It was found that the optimized composition of the anti-fogging coating was 2.78% of PVA and 0.84% of SA, which was capable of endowing the PE film great anti-fogging performance and good hydrophilicity with the water contact angle as low as 7.8°. Moreover, the coated film exhibited good transparency with the transmittance as high as 93.2%. The average fog degree was only 3.44%. The coating film showed high transparency in hot fog and had a good preservation effect for Zhangji strawberries. The simulation indicated that the average bonding capacity between the water and the coating was 57 times that of the original film. These findings demonstrated that the proposed PVA-SA coating had a high transparency, helped to enhance the wettability of the PE film without sacrificing its original transparency, and played a good preservation effect on fresh food. The anti-fogging mechanism of the hydrophilic coating was analyzed by simulation. The result showed that the coating had great prospects in anti-fogging performance of packaging films for fresh products.