Femtosecond laser-irradiation-induced phase change of a new amorphous Si(2)Sb(2)Te(3) film with a good thermal stability and low reset current is studied by coherent phonon spectroscopy. New coherent optical phonons (COP) occur as laser irradiation fluence reaches some threshold, implying laser-induced phase change emerged. The compositions in phase-changed area revealed by COP modes agree well with ones in reported annealed crystallized film, implying laser-induced phase change as crystallization. Pump fluence dependence of COP dynamics reveals good crystallization quality of the phase-changed film, exhibiting promising application of Si(2)Sb(2)Te(3) films in optical phase change memory. Acoustic phonons are also found and identified.