<p>This study explored the in vitro alleviation of the soluble and non-digestible Chinese yam polysaccharides (YP) with covalent selenite-grafting on the nonylphenol-induced cytotoxicity and barrier damage in rat intestinal epithelial (IEC-6) cells. Two grafted products YPSe-I and particularly YPSe-II possessed much higher Se contents than YP (0.803 and 1.486 <i>versus</i> 0.037&#xa0;g/kg), could alleviate the cytotoxicity of nonylphenol by causing higher cell viability but lower lactate dehydrogenase release and ROS production, and were capable of repairing the induced barrier damage through increasing transepithelial electrical resistance, reducing paracellular permeability, promoting the production and distribution of cytoskeleton F-actin, and up-regulating the expression levels of three tight junction proteins namely zonula occludens-1, occludin, and claudin-1. Meanwhile, the expression levels of two proteins namely p-p38 and p-JNK in the cells, which are crucial to the activation of the MAPK signaling pathway, were up-regulated by nonylphenol but down-regulated by YPSe-I and YPSe-II. The results consistently confirmed that YP and YPSe-II exhibited the respective lowest and highest activities in the cells to alleviate the nonylphenol-induced cytotoxicity and barrier damage, declaring that both YP selenization and higher selenite-grafting extent were the critical factors controlling the measured activities of YPSe-I and YPSe-II. Collectively, this selenite-grafting of YP endowed the selenized products with higher activity in the cells to reduce nonylphenol-induced cytotoxicity, especially to alleviate the induced barrier damage by inactivating the MAPK signaling pathway.</p>