Efficient separation of carbohydrates and lignin from lignocellulosic biomass, and further high-value conversion are still the main challenge of biorefinery. Oxygen-enhanced alkali treatment as a green method for separating polysaccharides and lignin from gramineous materials with environmental, economic and low energy consumption. Herein, oxygen-enhanced alkali technology was used to pretreatment corn stalk pith, and then realize high-value transformation. The results showed that oxygen-enhanced alkali treatment combined with acid precipitation, ethanol precipitation, enzymatic hydrolysis or ultrasonic can achieve clean, efficient separation and subsequent high-value transformation of various components of corn pith. The enzymatic efficiencies of solid and liquid polysaccharides were 75.42% and 50.52% respectively, and the structure of micro/nano-cellulose fiber is mostly flaky and granular. In addition, the separated lignin contains many small molecular compounds, which has the potential value of further utilization. In this study, oxygen-enhanced alkali treatment can achieve clean, efficient separation and subsequent high-value transformation of various components in corn stalk or lignocellulosic biomass, which has important practical significance.