In order to improve the measurement accuracy and realize the real-time mesurement speed of the laser self-mixing interferometer in a large range of displacement, advanced sinusoidal phase-shifting technique and the time-domain phase demodulation method are adopted. The electro-optic crystal modulator is used to realize the sinusoidal phase-shifting on the laser beam in the external cavity and the interference signal′s phase will be demodulated by the time-domain phase demodulation method. By combining the two together, it can meet the speed requirement in a wide range of displacement measurement process and implement the interferometer′s real-time measurement requirement at the same time. Experimentally, PI′s high-precision commercial electric displacement platform calibration results verified the sinusoidal phase modulation laser seif-mixing interferometer′s displacement measurement precision can reach less than 0.5 μm in the hundred mm large-scale displacement measuring process. In addition, the factors affecting the interferometer′s measurement speed in the real-time displacement measurement process is analyzed and the maximum speed of our system is obtained.