NOVELTY - Preparing black silicon based on liquid phase chemical reaction, comprises placing a silicon sheet into a corrosion solution, providing a metal ion compound having catalytic activity in the corrosion solution, texturing the surface of the silicon sheet by ion etching reaction under catalytic action to form the black silicon material having micro structure surface. The corrosion solution is a mixed solution of hydrofluoric acid and hydrogen peroxide. The mixing weight ratio of the hydrofluoric acid to hydrogen peroxide is 1: 3-6. The ion etching temperature is 5-85 degrees C.    USE - The black silicon is used in silicon-based solar battery.    ADVANTAGE - The black silicon material has large surface area, surface micro structures of silicon micro column, silicon micro particles and silicon micro holes. The absorption of the black silicon material at 300-2000 nm can be more than 90% and at 300-800 nm can be more than 95%. The silicon surface with nanoscale texturing on the silicon surface controls the absorbing wavelength and reflectivity, thus it improves the conversion efficiency of the silicon-based solar battery.    DETAILED DESCRIPTION - Preparing black silicon based on liquid phase chemical reaction, comprises placing a silicon sheet into a corrosion solution, providing a metal ion compound having catalytic activity in the corrosion solution, texturing the surface of the silicon sheet by ion etching reaction under a catalytic action to form the black silicon material having micro-structure surface. The corrosion solution is a mixed solution of hydrofluoric acid and hydrogen peroxide. The mass percent concentration of hydrofluoric acid is 1-20%. The mass percent concentration of hydrogen peroxide is 0.1-30%. The mixing weight ratio of the hydrofluoric acid to hydrogen peroxide is 1: 3-6. The metal ion compound having catalytic activity provided for etching reaction and added in the corrosion solution, comprises compounds made of gold, silver, iron, copper, nickel, zinc and/or tin. The ion etching temperature is 5-85 degrees C and the ion etching time is 1-60 minutes. The catalytic metal ion can be used individually, in a compound form or in a mixture of two or more metal ions.