The liquid crystal system represented by the organic molecule RM734 is a nematic liquid crystal with ferroelectric properties. In order to explore its response to light stimulation, the UV-visible absorption spectrum measurement and UV illumination experiment were carried out on the liquid crystal molecule. The results show that when the liquid crystal molecule is in the low temperature ferroelectric nematic phase, there is an absorption peak at 357 nm, and the peak absorbance is up to 1.74. The experimental phenomenon of illumination shows that it can undergo isothermal phase transformation when conducting photodegradation reaction under the UV light induction of 365 nm wave band, from low temperature ferroelectric nematic phase to high temperature traditional nematic phase, and this phase transformation behavior is repeatable. Further experimental results show that changing the polarization direction or intensity of the incoming polarized light can control the phase transition speed. In general, ferroelectric nematic liquid crystals with optical response ability are controllable to a certain extent, which broadens the application range of ferroelectric liquid crystals and provides new ideas for the application of their optical devices.