The invention provides a preparation method of a TinO2n-1 porous electrode. The method comprises the following steps: mixing TiH2 and TiO2, carrying out ball milling, drying and screening, carrying out sintering, dropping polyvinyl alcohol so as to obtain a precursor mixture, adding the precursor mixture into foam nickel, carrying out pressurization so as to obtain a pressing blank, carrying out sintering, welding a lead on the surface of the foam nickel, sleeving the outer side of the lead by a polyvinyl alcohol tube, packaging a TinO2n-1 pre-finished product by using an epoxy resin, and after the epoxy resin is cured, carrying out flat polishing, so as to obtain the TinO2n-1 porous electrode. The invention further provides application, namely electrochemical degradation on organic matters in organic wastewater. By adopting the preparation method, TiH2 is adopted as a reducing agent of TiO2, TiH2 is capable of reducing temperatures required by reactions, Ti atoms and H atoms are decomposed by TiH2 to directly join in TiO2 reduction, and reaction processes can be simplified; and the TinO2n-1 pre-finished product is of a porous structure, is large in specific surface area, high in electrolysis rate and high in content of Ti4O7, and the TinO2n-1 porous electrode is high in oxygen evolution potential, good in electrochemical stability and high in organic matter removal rate in electrochemical degradation of organic matters in organic wastewater, can be repeatedly used, and is long in service life.