The modern micro- and nanoelectronics development is expressed in the ever-growing need for increase in the density of information storage and the speed of its recording and reading. The recording information speed in based on magnetically ordered materials memory devices is determined by the magnetization switching speed. In [1], the possibility of magnetic order parameter switching under the single femtosecond laser pulse action was demonstrated. In the present moment it is the most effective method of influencing on the medium in extremely short times.  The use of ferroelectric materials will allow the creation of new more efficient and non-volatile memory devices. But for this it is necessary to solve the problem of ferroelectric order parameter ultrafast switching, which is still a problem at present. The reason is that there are no the same mechanisms in ferroelectric materials, which provide the ultrafast magnetization switching in magnetically ordered media.  Earlier we demonstrated the possibility of ferroelectric soft mode optical excitation in the ferroelectric-semiconductor crystal Sn2P2S6 [2]. It was also shown that when the soft mode is excited by a femtosecond laser pulse, ultrafast local laser heating does not occur [3].  In this paper, we demonstrate the photoexcited soft mode temperature dependence in the Sn2P2S6 crystal in the region of the phase transition temperature. The photoinduced soft mode frequency change in the ferroelectric phase transition temperature region is shown, which coincides with the literature data. In addition, the temperature dependence of the low-frequency acoustic phonon arising in a Sn2P2S6 crystal under the action of a femtosecond laser pulse is investigated. It is shown that the frequency of this phonon varies at the Curie temperature, which can be explained by a change in the phonon-phonon interaction with the soft mode during the structural phase transition.