  We study the Higgs phenomenology in the Peccei-Quinn invariant NMSSM
(PQ-NMSSM) where the low energy mass parameters of the singlet superfield are
induced by a spontaneous breakdown of the Peccei-Quinn symmetry. In the generic
NMSSM, scalar mixing among CP-even Higgs bosons is constrained by the observed
properties of the SM-like Higgs boson, as well as by the LEP bound on the
chargino mass and the perturbativity bound on the singlet Yukawa coupling. In
the minimal PQ-NMSSM, scalar mixing is further constrained due to the presence
of a light singlino-like neutralino. It is noticed that the $2\sigma$ excess of
the LEP $Zb\bar b$ events at $m_{b\bar b}\simeq$ 98 GeV can be explained by a
singlet-like 98 GeV Higgs boson in the minimal PQ-NMSSM with low $\tan\beta$,
stops around or below 1 TeV, and light doublet-higgsinos around the weak scale.
