Abstract: This paper reports the result of a study on the physical stability of injection 139. The conductivity of injection 139 was found to be sensitive to the coalescence of polyphase liposome. Therefore, by measuring the regularity of the conductivity change in injection 139, the physical stability of the polyphase dispersive system might be obtained. Using this method, the kinetic equation of coalescence of polyphase liposome in injection 139 (which describes the change of degree of dispersion, i.e. change of coalescence in the type of polyphase dispersion system), the activity energy for coalescence and the kinetic constants of coalescence of the dispersive particles in injection 139 were derived.At the same time, the distribution of particle size and the regularity of the change of particle size of injection 139 were determined with Coulter counter. The constitution of polyphase liposome was verified by the microscopic photographs.