Abstract: Among macromolecules with complex architectures, graft copolymers represent a special type in which multiple chains are densely attached to a linear backbone. Because of their compact branched structure and persistent cylindrical shape, such polymers have emerged as a unique class of nanostructured polymers in surfactant, stain-resistance, biomedical, nano and supramolecular science. However, there is still few robust methods for efficient synthesis of such polymers due to their inherently challenging synthesis, especially for asymmetric molecular double-brushes bearing different dense side chains attached to the polymeric backbone with Janus-type conformation. Most of the developed synthetic routes for graft copolymer are limited to the need of polymeric functionality transformation, polynorbornene backbones or special cyclic monomers. How to construct a versatile platform for preparing graft copolymers still keeps a challenge for chemists. The aim of this article is to review and highlight the progress of preparation of graft copolymers, especially for asymmetric molecular double-brushes. Recently, Prof. Xiaoyu Huang and co-workers in Shanghai Institute of Organic Chemistry (SIOC), Chinese Academy of Sciences, have given their unique answer and talented way. Atom transfer radical polymerization (ATRP) is a particularly attractive controlled radical polymerization (CRP) process covering broad monomers, meanwhile, Cu-catalyzed azide/alkyne cycloaddition (CuAAC) "click" reaction with their high specificity and nearly quantitative yields have gained a great deal of attention. Huang et al. found that the combination of ATRP and "click" reaction can be used to directly synthesize the asymmetric molecular double-brushes in one pot system, because either ATRP or "click" reaction employ the copper/ligand catalytic system. This work is a breakthrough for preparation of asymmetric molecular double-brushes.