A preparation method of a graphene nanoribbon on h-BN, comprising: 1) forming a h-BN groove template with a nano ribbon-shaped groove structure on the h-BN by adopting a metal catalysis etching method; 2) growing a graphene nanoribbon in the h-BN groove template by adopting a chemical vapor deposition method. In the present invention, a CVD method is adopted to directly prepare a morphology controllable graphene nanoribbon on the h-BN, which helps to solve the long-term critical problem that the graphene is difficult to nucleate and grow on an insulating substrate, and to avoid the series of problems introduced by the complicated processes of the transferring of the graphene and the subsequent clipping manufacturing for a nanoribbon and the like.