Abstract: The influence of surfactant on secondary atomization in the bag breakup regime of surfactant solution was studied experimentally by high-speed camera using aqueous surfactant solution as liquid medium and atmosphere as gas medium.The change of deformation and time characteristics were elaborated.The results showed that,in the aspect of deformation characteristics,as a crucial parameter of surfactant,the critical micelle concentration (CMC) has an important effect on secondary atomization;all deformation parameters like maximum dimensionless rim diameters (d_r,m/d₀),radial length (l_m/d₀),axial length (h_m/d₀),length-width ratio (l_m/h_m) of bag changed fast except that the largest droplet diameter deformation rate kept about 1.64 when the surfactant concentration was below the CMC.However,the variation of these parameters turned to be steady when the surfactant concentration exceeded the CMC.d_r,m/d₀ stabilized at about 4.16,l_m/d₀ stabilized at about 6.36,and l_m/h_m stabilized at about 1.53.