In traditional photonic Doppler velocimetry system, velocity information is generally obtained by off-line processing. The processing cycle is so long that the sensing system can’t be used in real time. From the principle of photonic Doppler velocimetry system, with the graphical language design of LabVIEW and the powerful numerical processing capacity of Matlab, using data acquisition cards and PC as acquisition and processing platforms, a signal acquisition and processing system is proposed and designed. The real-time data acquisition, on-line processing and display of velocimetry signal are realized.