The　instability　mechanisms　of　the　supported　liquid　membrane　using　Celgard　2500　membranes　as　support　and　tributyl　phosphate　dissolved　in　kerosene　as　carrier　for　phenol　transport　was　studied　by　electrochemical　impedance　spectroscopy.　Emulsion　formation　is　demonstrated　to　be　one　of　the　main　causes　for　the　instability　of　supported　liquid　membrane　in　the　present　system.　The　emulsion-facilitated　conditions,　such　as　higher　membrane　liquid　concentration,　faster　stirring　speed,　lower　salt　concentration　and　higher　HLB　value,　would　accelerate　the　degradation　of　supported　liquid　membrane.　Other　mechanisms　including　solubility　and　osmotic　pressure　work　together　to　increase　the　membrane　liquid　loss.　©　2009　Chemical　Industry　and　Engineering　Society　of　China　(CIESC)　and　Chemical　Industry　Press　(CIP).