  We introduce Hermite polynomial excitation squeezed vacuum (SV)
H_{n}(O)S(r)|0> with O=u a+v a^{{+}}. We investigate analytically the
nonclassical properties according to Mandel's Q parameter, second correlation
function, squeezing effect and the negativity of Wigner function (WF). It is
found that all these nonclassicalities can be enhanced by H_{n}(O)operation and
adjustable parameters u and v. In particular, the optimal negative volume
delta_{opt}of WF can be achieved by modulating u and v for n>=2,while delta is
kept unchanged for n=1. Furthermore, the decoherence effect of phase-sensitive
enviornment on this state is examined. It is shown that delta with bigger
ndiminishes more quickly than that with lower n, which indicates that
single-photon subtraction SV presents more roboustness. Parameter Mof
reservoirs can be effectively used to improve the nonclassicality.
