  Recently, a novel topological index, Sombor index, was introduced by Gutman,
defined as $SO(G)=\sum\limits_{uv\in E(G)}\sqrt{d_{u}^{2}+d_{v}^{2}}$, where
$d_{u}$ denotes the degree of vertex $u$.
  In this paper, we first determine the maximum Sombor index among cacti with
$n$ vertices and $t$ cycles, then determine the maximum Sombor index among
cacti with perfect matchings. We also characterize corresponding maximum cacti.
