Abstract: Two step anodic oxidation method was firstly used to prepare freestanding porous silicon. Then ZnO nanocrystal layer was deposited in the freestanding porous silicon using vacuum filtration method and hydro-thermal synthesis approach was used for further growth of ZnO nanocrystals finally. The morphology, element and luminescence properties of the samples were characterized by scanning electron microscope, X-ray energy dispersive spectrum analysis and photoluminence spectrum analysis. The results show that ZnO nanoparticles exist in the freestanding porous silicon and porous silicon/ZnO composites form successfully. Moreover, the electrochemical tests of the composites as a supercapacitor electrode was conducted by cyclic voltamerty, impendance spectrum and galvanostatic charge/discharge tests. The composites have good supercapacitor property. The specific capacitances can reach 15.7 F/g, with an increase of 120 times compared with the freestanding porous silicon.