  The interaction between the quantum emitter and topological photonic system
makes the photon behave in exotic ways. We here study the properties of a giant
atom coupled to two sites of a one-dimensional topological waveguide, which is
described by the Su-Schrieffer-Heeger (SSH) chain. We find that the giant atom
can act as an effective boundary and induce the chiral zero modes, which are
similar to those in the SSH model with open boundary, for the waveguide under
the periodical boundary. Except for the boundary effect, we also find that the
giant atom can lift energy degeneracy inside the energy bands of the SSH chain
and adjust spatial symmetry of the photon distributions for the states of the
dressed giant atom and waveguide. That is, the giant atom can be used to change
the properties of the topological environment. Our work may stimulate more
studies on the interaction between matter and topological environment.
