A new subclass of H-matrices, extended \(SDD_1\) ( \(ESDD_1\) ) matrices, is studied in this paper. The relationship between \(ESDD_1\) matrices and other subclasses of H-matrices is analyzed, and several properties of \(ESDD_1\) matrices are presented. Moreover, the infinity norm bounds of the inverse of \(ESDD_1\) matrices are derived, and a new infinity norm bound of the inverse of SDD matrices is provided. As applications, the error bound for the linear complementarity problems (LCP) of \(ESDD_1\) matrices is given. Finally, the effectiveness of corresponding results are illustrated by numerical examples.