The invention belongs to the electrochemical technical field, and relates to a preparation method for a tantalum-contained interlayer metallic oxide electrode. The electrode is suitable for occasions including steel plate high-speed electroplating, seawater electrolysis marine life pollution and damage prevention devices, sodium hypochlorite electrolysis production devices, sewage treatment, cathode protection and the like in the electrochemistry industrial field. The main process comprises three steps, namely substrate pretreatment, tantalum-contained interlayer preparation and oxide coatingpreparation: firstly, a tantalum-contained interlayer is prepared on a titanium substrate by adopting a thermal decomposition method, and then a mixed metallic oxide electro-catalysis coating is prepared on the tantalum-contained interlayer; the mass percent purity of the metallic titanium substrate is larger than 99%; and the process is simple and convenient to carry out, the metallic oxide electrode with larger size or more complicated structure can be prepared, and the tantalum-contained interlayer can better protect the titanium substrate, delay the titanium substrate inactivation, improve the stability of the oxide electrode and prolong the service life.