The invention relates to a porous electrode as well as a preparation method for conductive treatment and application thereof. Plant fibers and nanocellulose are introduced into a conventional electrode pulping and coating technological process, and a three-dimensional mesh structure is formed during the drying process of an electrode material by utilizing the excellent water absorption and water retention of the plant fibers and the nanocellulose. The porous electrode is further wetted and coated with conductive slurry, and a conductive path is formed along the three-dimensional mesh structureof the porous electrode, thereby improving the conductivity of the electrode, and significantly enhancing the energy density and power density of capacitors or lithium ion capacitors. The contradiction between electrochemical deposition, hydrothermal deposition and other electrode morphology control technologies and large-scale production is solved, and the technical problems of incapability of controlling the electrode morphology and the like in the conventional slurry coating process is solved. At the same time, the preparation process has the advantages of high efficiency and simplicity.