The　halophilic　archaeon,　Haloferax　mediterranei,　is　able　to　produce　polyhydroxyalkanoates　(PHAs)　in　large　quantities.　Along　with　the　synthesis　of　PHAs　by　H.　mediterranei,　an　extracellular　polymeric　substance　(EPS)　is　excreted　as　a　byproduct,　lowering　the　efficiency　of　the　production　of　PHAs.　In　this　experiment,　salinity　effects　on　the　carbon　distribution　to　synthesis　of　PHAs　and/or　EPS　were　explored　in　order　to　control　their　production.　It　was　found　that　high　NaCl　concentrations　inhibited　the　productivity　of　EPS　while　encouraging　the　productivity　of　PHAs.　The　optimal　salinity　for　the　growth　and　proliferation　of　H.　mediterranei　was　in　the　range　of　150-200　g　L-1.　EPS　productivity　decreased　from　371.36　to　319.74　mg　EPS　per　g　CDW　as　the　concentration　of　NaCl　increased　from　75　g　L-1　to　250　g　L-1.　However,　high　salinity　promoted　the　synthesis　of　PHAs.　When　the　NaCl　concentration　was　250　g　L-1,　the　intracellular　content　of　PHAs　reached　a　maximum　of　71.1%.　This　result　indicated　that　a　high　NaCl　concentration　significantly　stimulated　the　production　of　PHAs　while　depressing　the　production　of　EPS.　This　study　provided　a　possible　solution　to　adjust　the　carbon　distribution　to　the　synthesis　of　PHAs　and　EPS　by　H.　mediterranei　by　controlling　the　concentration　of　NaCl.