Hemicellulose is one of the most important natural polysaccharides in nature. Hemicellulose from different sources varies in chemical composition and structure, which in turn affects the modification effects and industrial applications. Grain and oil by-products (GOBP) are important raw materials for hemicellulose. This article reviews the modification methods of hemicellulose in GOBP. The effects of chemical and physical modification methods on the properties of hemicellulose biomaterials were evaluated. The potential applications of GOBP hemicellulose in films, hydrogel, Three-dimensional (3D) printing and adsorbent are discussed. Future research directions and recommendations are also proposed to provide theoretical foundations and technical support for the efficient utilization of these by-products.