Despite the numerous benefits of AX on the immune system and gut bacteria, the potential adjuvant activity of WEAX on immune responses has not been adequately investigated. In the present study, three kinds of WEAX with different structural features were obtained and their adjuvant potential on the specific cellular and humoral immune responses in ovalbumin (OVA) immunized mice were assessed. Our data demonstrated that WEAX had potent effects on innate and acquired immune responses through up-regulating the NK cell activation and promoting the Th2 type immune response. Furthermore, this study also elucidated the possible relationship between the adjuvant activity of WEAX and the structure. Compared with the other characteristics of the WEAX, we found that the immunomodulatory activity may be related to their content of ferulic acid, and not to the molecular weight.