THz wave band is located in the electromagnetic wave spectrum between infrared light and a millimeter of wave, the electromagnetism radiation in this frequency range has very special properties, such as in the object imaging, the medical treatment diagnosing, the environment detecting, the radio astronomy and the broad band mobile communication etc, and it has wide applied foreground in these fields. Recent a few years, the technology of the THz wave has obtained progress and development not only in the basic research but also in the application research, furthermore various THz radiation source basing the optical method increasingly showed the outstanding status in numerous the technology produced THz radiation by the predominant characteristic and outstanding merit. For the THz wave parameter oscillator it will be further optimized in exploring the happen, oscillation and enlarged mechanism of THz radiation and it will rapidly be developed toward realizing high-efficiency and high energy, structure severeness, brief continuous tuning and room temperature stabilizing operation.The contents of this text researching introduce the elementary excitation - the formation of the electromagnetic coupling field quantum , the meaning of the arouse the La Man scattering and dispersion curve setting out from the elementary excitation of the solid theory, elaborate the principle of THz wave parameter oscillator producing THZ wave applying arouse scattering of the phonon, and describe the arouse scattering of the electromagnetic coupling field quantum using Henry and Garrett of the wave coupling method to make a deduction the calculation formula of the THz wave parameter gain and carry out the numerical calculation for the expression. In addition, it detailedly discuss and analyze the temperature influence to THz wave. Through analyzing and researching, we can know the frequency of every spectrum peak minish, the position of spectrum peak move toward low wave number direction and the number of spectrum peak decrease with increasing the temperature. This reason mainly is the key coupling strength of the [Li-O], [Nb-O] in LiNbO_3 crystal and the interaction of ion in the crystal lattice is weaken with the increasing temperature strength, but the action of the optical phonon is closely interrelated with the [Li-O] key in crystal, that result in the Raman activity reducing of Al symmetry optical soft mold in the LiNbO_3 crystals, so as to appear to the phenomena of the THz wave gain lowering with the increasing temperature, this result provide a very valuable reference for the optimum design of the THz wave parametric oscillator.