Abstract: The stabilities of the adsorption films of the o/w emulsions were investigated with a home made drop stability apparatus in which isopropyl myristate (IPM) was used as the oil and Pluronic copolymers (L₆₁,L₆₄,F₆₈ and F₁₀₈),lecithin (PC) and their mixture were used as the emulsifier,respectively.The results show that Pluronic molecule with a long PEO block benefited the stabilization of the film.When single Pluronic copolymer was used as the emulsifier,however,the limited length of the PPO blocks restricted their bending to insert the oil drop,resulting in the reduction of the compactness of the molecules arranging at the oil/water interface because of the repulsion between the long PEO blocks.The addition of PC improved the arrangement of the emulsifier molecules at the oil/water interface and promoted them to pack tightly.Thus the long PEO blocks wrapped on the surface of oil drop stabilized the oil-drops in water.The present work has demonstrated that the mixed emulsifiers of F₆₈+PC or F₁₀₈+PC with 0.012 5 g/mL Pluronics and 0.016 7 g/mL PC can form a stable adsorption film at the oil/water interface.