The　purpose　of　the　present　study　was　to　investigate　the　effective　components　of　the　demulsifying　bacterial　strain　Bacillus　mojavensis　XH-1　and　its　demulsification　process.　Sodium　dodecyl　sulfate-polyacrylamide　gel　electrophoresis　(SDS-PAGE)　and　the　shotgun　LC-MS/MS　method　were　used　to　separate　and　identify　proteins　with　efficient　demulsification　activity.　The　zeta　potential　changes　of　the　emulsion　before　and　after　addition　of　the　biodemulsifier　were　tested,　and　the　relationships　between　oil-in-water　interfacial　tension,　the　demulsification　efficiency　and　the　biodemulsifier　structure　were　examined.　The　study　results　indicate　that　the　effective　biodemulsifier　components　were　extracellular　proteins　attached　to　the　cells　or　secreted　into　the　culture　solution　that　presented　as　a　50-80　kDa　band　observed　by　SDS-PAGE.　Six　of　the　proteins　were　unknown　or　unnamed,　and　the　demulsifying　functions　of　another　14　proteins　had　not　been　previously　reported.　The　main　demulsification　mechanisms　were　determined　to　be　solubilization　and　replacement.　When　the　concentration　of　the　biodemulsifier　was　low,　the　replacement　mechanism　dominated,　and　the　demulsification　ratio　increased　with　the　biodemulsifier　concentration.　Solubilization　dominated　when　a　high　concentration　of　biodemulsifier　was　provided,　and　the　demulsification　ratio　decreased　as　the　biodemulsifier　concentration　increased.