As one of the most challenging inflammatory diseases, the incidence of ulcerative colitis (UC) is increasing year by year, but the existing therapeutic drugs are not effective and lack of targeting. Nanomaterials are expected to become promising delivery system due to their good targeting effects. Here, we designed a nanomaterial sensitive to reactive oxygen species, which can be used to treat IBD, especially UC. It is a self-assembled polyether micelle that can be oxidized at the inflammation site where the concentration of reactive oxygen increases, and effectively release the encapsulated budesonide (Bud). Experiments have proved that for DSS-induced colitis, the synthetic drug-loaded nanoparticles have excellent therapeutic effects, can effectively repair intestinal barrier, and significantly improve the damaged colon tissue. At the same time, it has a beneficial regulatory effect on inflammatory factors. Molecular mechanism studies have shown that it achieves its therapeutic effects by activating the peroxisome proliferators-activated receptors-γ (PPAR-γ) pathway and inhibiting the nuclear factor (NF)-κB pathway. This study proves that oral nano-micelles have an important impact on improving the efficacy of UC treatment drugs and have far-reaching significance for the targeted treatment of gastrointestinal diseases.