OBJECTIVE: To investigate the effect of poloxamer 188 as co-emulsifier on the pharmaceutical property of emulsion.METHODS: Diclofenac sodium was used as model drug and poloxamer 188 as co-emulsifier,the emulsion was prepared by high pressure homogen-colostrum pH adjusting method,with its entrapment efficiency,particle size,?-electric potential etc determined.RESULTS: The emulsion which was added with poloxamer 188 showed decreased entrapment efficiency and ?-electric potential but increased particle size as comapred with the one without poloxamer 188.CONCLUSION: The pharmaceutical property of emulsion wouldn't necessarily be enhanced by adding poloxamer 188 as co-emulsifier.