  The light scalar meson nonet above 1 GeV ({\it i.e.\}the $a_{0}$,
$K^{\ast}_{0}$ and $f_{0}$) are studied within the framework of QCD sum rules.
In conventional QCD sum rules, the calculated masses of this nonet are
degenerate, and the mass of $K^{\ast}_{0}$ is always larger than the $a_{0}$ in
contradiction with the observed spectrum. After improving the correlation
function by including instanton effects, the masses are well separated from
each other. In particular, our results shows glueball content plays an
important role in the underlying structure of $f_{0}(1500)$. The decay
constants are also discussed.
