  In the framework of the simplest little Higgs model (SLHM), we perform a
comprehensive study for the pair productions of the pseudoscalar boson {\eta}
and SM-like Higgs boson h at LHC, namely gg(b\bar{b})-> {\eta}{\eta},
gg(q\bar{q})-> {\eta}h and gg(b\bar{b})-> hh. These production processes
provide a way to probe the couplings between Higgs bosons. We find that the
cross section of gg-> {\eta}{\eta} always dominates over that of b\bar{b}->
{\eta}{\eta}. When the Higgs boson h which mediates these two processes is
on-shell, their cross sections can reach several thousand $fb$ and several
hundred $fb$, respectively. When the intermediate state h is off-shell, those
two cross sections are reduced by two orders of magnitude, respectively. The
cross sections of gg-> {\eta}h and q\bar{q}-> {\eta}h are about in the same
order of magnitude, which can reach $\ord{(10^2fb)}$ for a light {\eta} boson.
Besides, compared with the SM prediction, the cross section of a pair of
SM-like Higgs bosons production at LHC can be enhanced sizably. Finally, we
briefly discuss the observable signatures of {\eta}{\eta}, {\eta}h and hh at
the LHC, respectively.
