The invention discloses a preparation method of a thin film electrode based on a covalent organic frame material, and relates to the field of material preparation. The method comprises the following steps: firstly a nitrogen-rich covalent organic frame material with fully conjugated carbon-carbon double bonds is synthesized; then the prepared covalent organic frame material and the commercializedsingle-walled carbon nanotube are dispersed by N, N-dimethylformamider to obtain a dispersion; then the dispersion is added to an electrode template and the thin film electrode is obtained by vacuum pumping and filtering; and finally the obtained thin film electrode is transferred to a flexible substrate, and vacuum drying is performed so as to obtain a flexible electrode which can be used for manufacturing a flexible micro supercapacitor. The preparation method has the advantages of easy operation, simple equipment and large-scale preparation. The shape of interposer finger is applied to makethe electrode spacing as small as possible and the device as miniaturized as possible; and the specific area capacitance can be up to 15.2 mF.cm<-2> so as to have great application potential in supercapacitors.