  We discuss the scale-free property of Wilson's numerical renormalization
group(NRG) for the Kondo impurity problem. The single-particle state of the
effective Hamiltonian with a cutoff $\Lambda$ is described by the wavepacket
basis having the scale free property; The energy scale of the system can be
controlled by the lattice translation of the wavepacket basis with no reference
of rescaling of the lattice space. We also analyze the role of the Kondo
interaction in the context of wavepacket basis and then discuss the scaling and
renormalization of the Kondo coupling. In addition, we clarify the role of the
edge state in the lowest energy scale of Wilson NRG.
