Abstract: Liquid mixing behavior is very complex and has great influence on the mass transfer process in the column packed with compound packing (125X+250Y).Until now the study of liquid mixing behavior in structured packing is far from enough.This paper provides experiment data for column design and process control.Liquid mixing behavior is investigated by using salt tracer technique.The axial and radial diffusion coefficients are obtained on the basis of diffusion models.It is found that liquid diffusion coefficients increase with liquid velocities and are insensitive to the change of gas velocities.