An optical measuring technology and its data processing method for the discharge velocity measurement of industrial flue gas are introduced,using the optical sc intillation signals caused by the random fluctuations of particulate concentration field.Under the influence of t urbulence,the cross correlation of optical scintillation signals,which is based on the separate double optical path measuring system structure,is analyzed,and the theoretical expression of the correlation function is acquired .The single circular linked list is adopted as the data accessing structure to implement the signal data sliding in time domain,and it can satisfy the requirements of real time and average simultaneously.The value of the optica l scintillation cross correlation is calculated by the fast Fourier transform (FFT).An implementation method of para llel one-dimensional FFT using advanced vector extensions (AVX) instructions is proposed,and the FFT calculati ng speed is doubled on the computing platform which is based on the Intel i7CPU.Finally,the field test r esults show that the flow velocity measured by the proposed technique in this paper is consistent well with the value tested by Pitot tube.It verifies the effectivenesses of this optical measuring technology and its data processing method.