  In this paper, we study isometric actions on finite-dimensional CAT(0) spaces
for the Higman-Thompson groups $T_n$, that are generalizations of Thompson's
group $T$. It is known that all semi-simple actions of $T$ on complete CAT(0)
spaces of finite topological dimension have global fixed points. After this
result, we show that all semi-simple actions of $T_n$ on complete CAT(0) spaces
of finite topological dimension have global fixed points. In the proof, we
regard $T_n$ as ring groups of homeomorphisms of $S^1$ introduced by Kim,
Koberda and Lodha, and use general facts on these groups.
