  We fabricated superconducting FeSe wires by the chemical-transformation PIT
process. The obvious correlation between annealing temperature and phase
transformation was observed. Annealing above 500^{\circ}C produced wire-core
transformation from hexagonal to tetragonal phase. Furthermore the hexagonal
phase completely transformed into the tetragonal phase by annealing at
1000^{\circ}C. With increasing annealing temperature, the superconducting
property was dramatically improved, associated with the evolution of the
tetragonal phase.
