The present invention relates to a flaky graphite-based polymer nanocomplex for preparation of a polymer complex, and more specifically, to a complex to which a polymer is stably bonded by surface-modifying, with a catecholamine, flaky graphite having a structure with nanoparticles crystallized at a high density on the surface. If the complex is dispersed in a target polymeric resin, preferably, in a homogeneous polymeric resin which is bonded to the complex, the complex is dispersed in the polymeric resin homogeneously and evenly, thereby being capable of obtaining a composite having excellent function in conductivity, thermal conductivity, etc.