A lignocellulose nanofibril material, a stable foam system based thereon, a preparation method and an application thereof are provided. The lignocellulosic nanofibril material includes the following components: 0.5-20 wt % of wood flour, 0.1-10 wt % of (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl, 2-25 mmol/g of an oxidant, 6-15 wt % of NaBr, and the remaining is water. The stable foam system based on the lignocellulosic nanofibril material includes: 0.1-1.0 wt % of the lignocellulosic nanofibril material, 0.2-1.0 wt % of a surfactant, 0.1-10 wt % of sodium chloride, 0.1-1.0 wt % of calcium chloride, 0.1-1.0 wt % of magnesium chloride, 0.1-1.0 wt % of sodium sulfate, and a balance of water.