Abstract: To forecast the possible parameter ranges of interphase dispersed zone (IDZ) process and abrupt change of liquid-liquid mass transfer rate,the dynamic characteristics of a molecular diffusion model are considered in this paper.We applied the bifurcation theory of planar dynamical system,Laplace transform and maple software to investigate the model.We have given the phase portraits of the system under one group of control condition.The results obtained will play an important directive role in the study of IDZ model.