  In this article, we assume that the nonet scalar mesons below $1\,\rm{ GeV}$
are the two-quark-tetraquark mixed states and study their masses and pole
residues using the QCD sum rules. In calculation, we take into account the
vacuum condensates up to dimension 10 and the $\mathcal{O}(\alpha_s)$
corrections to the perturbative terms in the operator product expansion. We
determine the mixing angles, which indicate the two-quark components are much
larger than $50\%$, then obtain the masses and pole residues of the nonet
scalar mesons.
