The invention provides a full titanium nitride current collector/electrode supercapacitor and a preparation method thereof, which belong to the technical field of new energy materials and devices. Thepreparation method comprises the steps of: firstly, cleaning and removing impurities on the surface of a substrate; then depositing a TiN thin film with high density and high conductivity on the surface of the substrate as an electron transport current collector material, changing thin film surface atomic diffusion, nucleation growth and the like mechanisms through regulating and controlling deposition process parameters, and directly continuing the growth of a layer of a porous and low-conductivity TiN thin film as an electrode material on the current collector. The current collector and theelectrode undergo TiN continuous growth, the performance of the materials is cut through simply changing the deposition process parameters of the thin film, the preparation method has the advantagesof simple and feasible process, low cost, variety selections of thin film deposition technologies and high process applicability, solves the problems of delamination cracking and large contact resistance caused by poor adhesion between dissimilar current collectors and the electrode materials, lattice mismatch and difference in thermal expansion coefficients, and can greatly improve the power density, thermal stability and long-term service reliability of the supercapacitor.