extremal cacti with respect to sombor index

Recently, a novel topological index, sombor index, was introduced by gutman, defined as $so(g)=sumlimits_{uvin e(g)}sqrt{d_{u}^{2}+d_{v}^{2}}$, 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.