The Raman excitation plus laser induced electronic fluorescence air flow velocimetry system is constructed. The second harmonics of Nd∶YAG laser and stimulated Raman scattering in O2 are employed as “tagging” laser source. The tagged line was interrogated with an ArF excimer laser. The laser-induced fluorescence images from tagged lines in O2 and air are captured by an intensity-CCD Camera. The velocity measurement of O2 jet is carried out.