Abstract: The fluorescence intensity distributions in water tank are obtained for con-centration measurement by a PLIF technique, and a two-dimensional digital calibrationequation and method are then proposed in order to account for the nonuniform distributionand attenuation of intensity of a laser thin. Based on the above,the concentration field ofround turbulent jet is measured and calibrated. Finally, the results of jet are analyzed andcompared with those of the semi-empirical theory.