The invention discloses a silybin purification method. The silybin purification method comprises the following steps: taking silybum marianum seed skins, crushing the material, adding ethanol according to the solid-liquid ratio of 1 kg: 2L, and performing ultrasonic extraction for 2 h at the temperature of 40 DEG C; then transferring the material liquid into a soxhlet extractor, adding an ethyl alcohol solution of 5-7 BV, performing extraction for 4 h at the temperature of 60 DEG C, performing water-bath rotary evaporation on an extract at the temperature of 50 DEG C for 2-4 hours, then placing the material under room temperature, filtering the material, and dissolving the material by 2-4 BV methanol, placing the material at the temperature of 5-10 DEG C for crystallization for 48-72 h, refiltering the material, performing cold water washing on a filter cake, and then performing vacuum drying at the temperature of 50 DEG C for 8 hours to obtain silybin with purity being greater than or equal to 97%. The method has the advantages of simple required equipment, clear process, easy realization, and low production cost, and the prepared silybin has the advantages of good quality, high purity, and obvious economic benefit.