The invention discloses a method for preparing L-arabinose by taking corn bran as the material, belonging to the technical field of functional sugar. The method includes the steps of: stewing: stewing the material of corn bran in alkali liquor; acid treatment: processing the stewed corn bran through oxalic acid and collecting the hydrolysate; neutralization: adding aqueous calcium carbonate solution, neutralizing, preserving the heat and pump filtrating to get neutralized fluid; decoloration: decoloring the neutralized fluid through active carbon to obtain decolored fluid; desalination and impurity removal: treating the decolored fluid through cation and anion exchange resins to desalt and purify the decolored fluid so as to obtain primary exchange fluid; vacuum concentration: concentrating the primary exchange fluid under decompression condition to obtain primary evaporating fluid; secondary decoloration: pump filtering after decoloration to obtain secondary decolored fluid; secondary desalination: treating the secondary decolored fluid through cation and anion exchange resins to desalt and purify for a second time to obtain secondary exchange fluid; chromatographic fractionation: vaporizing and concentrating the secondary exchange fluid and then conducting chromatographic fractionation; concentrating the exchange fluid under decompression condition after the chromatographic fractionation and cooling naturally to room temperature; and centrifuging and drying: centrifuging and drying to obtain arabinose crystals.