<p>Surface treatment can prolong the service life of coir geotextiles, but they may also alter the mechanical behavior at the geotextile-soil interface. This study conducted pullout tests on anti-corrosion treated coir geotextiles (ACGs) embedded within transparent sand to analyze the mechanical properties of interface between ACGs and sand. The influence of normal stress, anchorage length, grid size, and weaving process on the interface mechanics was investigated. The analysis results at both macroscopic and mesoscopic scales indicate that increasing the normal stress and anchorage length can enhance the pullout force and ‌shear band thickness of ACGs. However, this enhancement effect gradually diminishes as the failure of ACGs pullout progresses. A larger grid size of ACGs leads to a decrease in pullout force and shear band thickness, indicating a decline in the reinforcement effect. Additionally, the anti-corrosion treated non-crossed coir geotextiles exhibit higher peak pullout force and larger shear band thickness compared to the anti-corrosion treated crossed coir geotextiles, demonstrating superior reinforcement properties.</p>