NOVELTY - A crystalline silicon solar cell preparing method involves preparing bionic photonic crystal light trapping structure and a multilayer antireflection coating. The structure is combined with the anti-reflection structure. The front surface of a silicon wafer is placed in oven after covered with scales template wafers into atomic layer deposition (ALD) and allowed into an annealing furnace. The ALD method is performed. The first silicon wafer is soaked in lysine solution, the wafer side is contacted with silicon and doped silicon oxide particles colloidal solution to obtain a finished product.    USE - Method for preparing crystalline silicon solar cell.    ADVANTAGE - The prepared solar cell has increased efficiency, reduced cell slice thickness and reduced cost.    DETAILED DESCRIPTION - A crystalline silicon solar cell preparing method involves preparing bionic photonic crystal light trapping structure and a multilayer antireflection coating. The bionic photonic crystal light trapping structure is combined with an anti-reflection structure by selecting butterfly wings for the removal of inorganic salts, and placed in 5-10 wt% sodium hydroxide solution for 60-200 minutes for the removal of organic scales on a dark green area, placed in 3-10 wt.% dilute hydrochloric acid for removal of protein and ether. The front surface of the silicon wafer is placed at 30-60 degrees C in oven for 40-80 minutes after covered with scales template wafers into the atomic layer deposition (ALD) in the reaction chamber, at 100-300 degrees C under after deposition on the alumina wafer, allowed into an annealing furnace, calcined at 300-600 degrees C in air for 2-5 hours to remove the scales stencil. The ALD method is performed at 100-300 degrees C to continue white multilayer film of alumina and aluminum nitride deposited on the photonic crystal surface of the wafer front surface, a single layer of alumina and silicon nitride having thickness of 2-4 nm, and the total thickness of the multilayer film of 30-80 nm. The first silicon wafer is soaked in 5-15 wt% aqueous lysine solution for 1-10 minutes to increase the adhesion of the particles, followed by deionized water rinse and drying in 75-85% humidity environment, the wafer side is contacted with silicon and doped silicon oxide particles colloidal solution for 5-120 minutes to obtain a finished product, where the particle concentration in the wafer surface is 4x 108-2x 109cm-2.