  The structure of $d^*(2380)$ is re-studied with the single cluster structure
in the chiral SU(3) quark model which has successfully been employed to explain
the $N-N$ scattering data and the binding energy of deuteron. The binding
behavior of such a six quark system is solved by using a variational method.
The trial wave function is chosen to be a combination of a basic spherical
symmetric component of $[(0s)^6]_{orb}$ in the orbital space with
$0\hbar\omega$ excitation and an inner structural deformation component of
$[(0s)^5(1s)]_{orb}$ and $[(0s)^4(0p)^2]_{orb}$ in the orbital space with
$2\hbar\omega$ excitation, both of which are in the spatial [6] symmetry. It is
shown that the mass of the system is about $2356$ MeV, which is qualitative
consistent with the result both from the two-cluster configuration calculation
and from the data measured by the WASA Collaborations. This result tells us
that as long as the medium-range interaction due to the chiral symmetry
consideration is properly introduced, the mass of system will be reduced in a
rather large extent. It also implies that the observed $d^*$ is a six-quark
bound state with respect to the $\Delta\Delta$ threshold, which again supports
the conclusion that $d^*$ is a hexaquark dominant state.
