Based on principle of Digital Phase Generated Carrier (DPGC) modulation, laser interference vibration measurement system and its signal demodulation on software and hardware platform were established. Taking the 24 bit data acquisition device and 64 bit PC processor as the core of hardware circuit, real-time data acquisition of reference waveform generation and the signal for measurement was realized. DPGC algorithm was established by using LabVIEW software workbench, and then vibration signal real-time demodulation was realized. The experiment results indicate that the DPGC signal demodulation scheme based on PC can reduce drift and noise by traditional analog PGC hardware circuit such as analog multiplier and differentiator, enhance accuracy of signal demodulation and improve signal-to-noise of system. High accuracy measurement of the low-frequency vibration signals ranging from 10~200 Hz comes true. The measuring resolution is better than 0.14 nm and the dynamic range is 120 dB.