<p>Fogging on agricultural greenhouse covering films reduces solar transmission, resulting in insufficient photosynthetically active radiation and hindering crop growth. In this study, a long-acting antifogging composite film was developed by incorporating diatomite (DE) and sorbitan tristearate (STS) into low-density polyethylene (LDPE). The introduction of STS enabled the surface of LDPE to undergo a transition from hydrophobic to hydrophilic. The film has the ability of preventing fogging and increasing solar irradiation inside the greenhouse by 15%. On the 30th day of the hot fog test, the failure area of the film was only 20%, and the introduction of DE reduced the diffusion coefficient of STS from 0.2 to 0.06&#xa0;cm ²&#xa0;min⁻¹. Rheological properties and crystallinity testing revealed the interaction mechanism between STS and LDPE molecules. Greenhouse cultivation experiments showed that the chlorophyll content of Chinese cabbage (<i>Brassica rapa ssp. chinensis</i>) and spinach (<i>Spinacia oleracea</i>) grown under the antifogging film increased by 24% and 30%, respectively. This antifogging film can be produced on a large scale using the casting method and offers significant potential for improving the quality of greenhouse crops.</p>