The pores with tunable sizes and densities have been prepared in the conductive layer of FTO glasses while keeping the conductivity and transparency almost unvaried, by immersing the FTO glasses coated with Zn powder in the mixed aqueous solution of HCl and ethanol. The average pore size and density can be continuously tuned in the ranges of 22-120 nm and 9-120/mu m(2), respectively, by simply adjusting the Zn concentration and/or ethanol volume ratio. The etching mechanism based on the oxidation of Zn by SnO2 (competing with HCl) has been revealed. Compared with FTO, the porous FTOs made here can greatly increases the detection sensitivity of H2O2 up to 3.7 times, when they work as the host substrate of NiO.