A method is proposed to use cross-correlation to measure the spatial transverse flow rate. By setting the scanning patterns X and Y based on the spectral domain optical coherence tomography, the absolute value of the flow rate is obtained according to the mathematical relation of the cross-correlation between the adjacent Ascans with the spatial transverse flow rate. The measuring principle of this method is elaborated. The transverse flow rate component distribution of the cross section is described through the simulation experiment using a capillary. It is demonstrated that the measured mean value of the transverse flow rate is in accordance with the set value using the syringe pump.