  In mean field approximation, we study a chiral soliton of the linear sigma
model with two flavors at finite temperature and density. The stable soliton
solutions are calculated with some appropriate boundary conditions. Energy and
radius of the soliton are determined in a hot medium of constituent quarks. It
is found that for $T<T_c$, the energy of the soliton $E^*$ is less than the
energy of three constituent quarks $3M_q$, but with the increasing of
temperature, the difference between $E^*$ and $3M_q$ becomes smaller and
smaller, once $T>T_c$, there is a sharp delocalization phase transition from
hadron matter to quark matter coincident with the restoration of chiral
symmetry. In the transition region, the thermodynamic properties show large
discontinuities which is an indication for a first-order phase transition.
