There are many monitoring methods of Fiber Bragg Grating (FBG) seismic waves. From the perspective of the construction of its detection system, unbalanced M-Z waveguide demodulation affects the construction of the detection system. Then, the collected data are effectively analyzed by the computer to achieve the specific graphic of seismic waveform. During the analysis and simulation of unbalanced M-Z waveguide demodulation, the phase modulator is effectively demodulated, so it will be set by the modulation depth and modulation frequency. Therefore, waveform graph is confirmed because seismic wavelength does not migrate. Besides, 3*3 coupler demodulation seismic detection system constructs the formation path of arrayed FBG seismic waves. The formation process of seismic waves can be more vivid by its simulation process, achieving the aim of monitoring more comprehensively to the seismic waves. Through the above research process, the monitoring process of FBG seismic waves becomes more effective and distinct, and the science of the monitoring process can be fully guaranteed. Moreover, the research and exploration of this paper further develops the monitoring methods of FBG seismic waves, laying a solid theory foundation for the future studies. Meanwhile, this paper also promotes to improve continuously the effectiveness of the formation process of seismic waves.