The present invention discloses a system and method for polarization observation wall of the optical element, wherein the internal electric field produced is low. The present invention is the irradiation of the irradiation light source in a predetermined direction; Signal generating unit for generating an electrical signal of known waveform; Signal control unit for controlling an electrical signal such that the electrical signals are pre-determined time constant generation unit; Located on the flow of the irradiation to enable the observation of the polled sample light source, a sample support portion for applying an electric signal to the sample; And the sample observing the pattern according to the polarization wall of, and in consideration of the measured minute extreme characterized in that it comprises a polarization wall observed to measure at least one of a shape, the moving distance of the polarization wall, and the moving speed of the polarization wall of polarization wall It provides a system for the polarization observation wall. According to the invention, it can be distinctly observed in real time, the polarization reversal process of the internal electric field, wherein all the low ferroelectric optical single crystal. In addition, this allows for producing the wavelength conversion element is the wavelength conversion efficiency higher quasi phase matching element, a laser display. Wall polarization observation, polarization reversal, liquid electrode, ferroelectric, lithium niobate, MgSLN (Mg-doped Stoichiometric Lithium Niobate), quasi-phase matching (Quasi Phase Matching), polling (electronical poling), the optical element