NOVELTY - Preparing light trapping structure with hydrophobic silicon surface comprises (i) cleaning the silicon by using the hot sodium hypochlorite solution to oxidize the greasy dirt on the surface; (ii) corrugating the silicon, taking potassium hydroxide and isopropanol to form alkaline corrosive, and etching the pyramid suede; (iii) carrying out silver mirror reaction to plate the sliver by adding the silver nitrate solution in a reaction container; (iv) catalyzing and etching by taking the precious metal nano particle; (v) removing the sliver remained on the surface; and (vi) vacuumizing.    USE - The method is useful for reducing the transmission rate of the visible light which is 380-780 nm to 5%.    ADVANTAGE - The method: controls the wet etching in constant temperature and is simple; has superhydrophobic performance; and increases the efficiency of the silicon and thin film solar cell. The silicon surface obtained has higher antireflection effect and attains the contact angle on the surface of the (100) silicon wafer to 110 degrees .    DETAILED DESCRIPTION - Preparing light trapping structure with hydrophobic silicon surface, comprises (i) cleaning the silicon by using the hot sodium hypochlorite solution to oxidize the greasy dirt on the surface, removing the oxidized greasy dirt by using the hydrogen fluoride, and then cleaning by using deionized water or ultra-pure water to obtain the clean silicon surface; (ii) corrugating with the alkaline solution, taking potassium hydroxide (1 wt.%) and isopropanol (8%) to form alkaline corrosive to corrode for 30-60 minutes in water bath in terms of (100) silicon wafer, and etching the pyramid suede; (iii) carrying out silver mirror reaction to plate the sliver by adding the silver nitrate solution in dropwise manner in the reaction container, controlling the concentration to 1-2 wt.%, gradually adding the aqueous ammonia in dropwise manner whose concentration is 2 wt.%, controlling the pH at 8-9, continuously agitating until the generated deposit is disappeared, then adding the glucose or acetaldehyde solution in dropwise manner, placing in water of 80 degrees C, and coating a layer of silver on the silicon wafer; (iv) catalyzing and etching by taking the precious metal nano particle by soaking the sliver-plated silicon wafer in the acid corrosive, where the monocrystalline silicon wafer of (100) and (111) in the acid corrosive is with or without air bubble, the sliver is not coated, and there is no corrosion effect; (v) removing the sliver remained on the surface by using the ultrasonic cleaning method, then soaking for 30 minutes by using nitric acid whose concentration is 20-40 wt.%, and completely removing the sliver, cleaning with deionized water, and observing black phenomenon on the surface, preparing the light trapping structure with hydrophobic silicon surface; and (vi) vacuumizing and storing in the dryer.