Abstract: The effect of dense spray on drop size measurement by light scattering technology was studied by using Malverm instrument with five duplicated internal mixing airblast atomizers aligned with laser beam.The correction factor data for multiple scattering were obtained.By regression analysis,an empirical equation was obtained which correlated the correction factor as a function of obscuration(OBS),Sauter Mean Diameter under dulite spray condition SMD_o and drop size distribution parameter for Rosin Rammler distribution under dilute spray condition N_o. The experimental data showed definitely that the correction factor is not only a function of OBS,SMD_o,as proposed by Lee Dodge,but also is a function of N_o.The correlation fits the experimental data very well,and can be used for practical purposes to correct the data from Malvern drop sizer at high obscuration conditions.