This peper introduces method and its relative apparatus of using laser induced fluorescence to measure the most traverse Probable velocity and veleocity distribution of metal atomic vapor born in vacuum chamber by means of the isotope spectrumtranslation and CCD device.In the CaSe Of the vapor model of 4×6 mm2,the experiment shows: the most transverse probable velocity increases linearly with x approximately and its distribution is not affeCted by the heating power; the transverse velocity distribution of atom density flux meets normal function and the FHWM of velocity varies with the heating power.