  We study the $a_1a_1$ and $Za_1$ decay channels of the next-to-lightest
CP-even Higgs boson $h_2$ of the NMSSM at the LHC, where the $h_2$ is produced
in gluon fusion. It is found that while the $h_2$ discovery is impossible
through the latter channel, the former one in the $ 4\tau$ final state is a
promising channel to discover the $h_2$ with masses up to around 250 GeV at the
LHC. Such a discovery of the $h_2$ is mostly accompanied with a light $a_1$,
which is a clear evidence for distinguishing the NMSSM from the MSSM since such
a light $a_1$ is impossible in the MSSM.
