Abstract: Antarctica contains numerous scientific mysteries, and the Antarctic ice sheet and its underlying bedrock contain important information about the geological structure of Antarctica and the evolutionary history of the ice sheet. In order to obtain the focus of these scientific explorations, the Antarctic drilling engineering is constantly developing. The drilling fluid performance directly determines the success or failure of drilling engineering. In order to enhance the poor performance for drilling fluids due to poor dispersion stability and easy settling of organoclay at ultra-low temperatures, the small-molecule wetting agent (HSR) for drilling fluid suitable for Antarctica was prepared by oleic acid, diethanolamine and benzoic acid as raw materials. Its chemical structure, properties and action mechanism were investigated by various experimental methods. The experimental results showed that 2% HSR could improve the colloidal rate for drilling fluid from 6.4% to 84.8%, and the increase rate of yield point was up to 167%. Meanwhile, it also made the drilling fluid excellent in shear dilution and thixotropy. In addition, 2% HSR could increase the density from 0.872 to 0.884 g/cm3 at −55 °C. And the drilling fluid with 2% HSR had a good thermal conductivity of 0.1458 W/(m·K) at −55 °C. This study gives a new direction for the research of drilling fluid treatment agents suitable for the Antarctic region, which will provide strong support for the scientific exploration of the Antarctic region.