  We present a lattice QCD determination of masses of the conjectured
H-dibaryon $m_H$ at nine different temperatures $T/T_c =0.24, 0.63, 0.76, 0.84,
0.95, 1.09, 1.27, 1.52, 1.90$. In the meantime, the masses of baryon $N$,
$\Sigma$, $\Xi$ and $\Lambda$ at different temperatures are also computed.
  The simulation is performed on anisotropic lattice with $N_f=2+1$ flavours of
clover fermion at quark mass which corresponds to $m_\pi=384(4) {\rm MeV} $.
The thermal ensembles were provided by the FASTSUM collaboration and the zero
temperature ensembles by the Hadspec collaboration. We also calculate the
spectral density of the correlation function of those particles.
  The spectral density distributions show rich peak structure at the lowest
temperature, while at intermediate temperatures, the mass values of those
particles obtained by extrapolation method reflect a two-peak structure.
  While the spectral density for octet baryon becomes smooth at $T/T_c = 1.27,
1.52, 1.90$, the spectral density for H-dibaryon becoms smooth at $T/T_c =
1.90$.
  At $T/T_c =0.24 $, the mass difference of H-dibaryon and $\Lambda$ pair
$\Delta m = m_H - 2\,m_{\Lambda} $ is estimated to be $\Delta m = -14.6(6.2)
{\rm MeV}$ which suggests there exists a bound H-dibaryon state.
