We have researched a new Pt/TiO₂-CN_X gas diffusion electrode which was used as cathode in energy-saving and environmentally friendly electrodeposition of manganese dioxide instead of the traditional cathode. The Pt/TiO₂-CN_X GDE has high activity and durability. We synthesized Pt/TiO₂-CN_X catalyst by chemical method and then make the Pt/TiO₂-CN_X gas diffusion electrode. The Pt/TiO₂-CNX GDE is three-layer structure which consists of Pt/TiO₂-CN_X catalyst layer, carbon paper and gas diffusion layer. The Pt/TiO₂-CN_X GDE is about 0.6mm. The Pt/TiO₂-CN_X gas diffusion electrode was used in 30g/dm³ H₂SO₄ +120g /dm³ MnSO₄ at 80°C. The electrolysis was carried out at 0.7 V, showing energy saving drop by 60% comparing to the traditional cathode (Cu). The Pt/TiO₂-CNx GDE as cathode can save energy about `60% more than 800 h. The section pictures of Pt/TiO₂-CNx GDE have almost no change for 100h, 200h and 400h. And there is no crack on the surface of Pt/TiO₂-CNx GDE in 100h, 200h and 400h, however, the surface of Pt/TiO₂-CNx GDE has some small cracks in 800h. The Pt/TiO₂-CNx GDE has great potential to be used as the cathode in electrodeposition of the MnO_2.B