Abstract: A new mathematical model for predicting the Murphree tray efficiency in the presence of liquid weeping is proposed by taking account of the uneven distribution of liquid velocity and unequal eddy diffusivities in Z and W direction on a tray.Typical calculation results indicate that the Murphree tray efficiency in the presence of liquid weeping depends on the following factors: weeping fraction ε, Pe, E_(OG), λE_(OG) and K = D_w/D_l. The discussions are useful for scale up design and commercial production.