The　high　cost　of　polyhydroxyalkanoate　(PHA)　production　significantly　limits　the　large-scale　industrial　production　of　PHA.　In　this　regard,　applying　static　magnetic　field　(SMF)　to　increase　PHA　productivity　could　be　a　novel　approach.　The　study　explored　the　biological　magnetic　effects　of　H.　mediterranei　for　PHA　production.　A　magnetic　window　for　PHA　synthesis　was　found　under　110　mT　SMF,　at　which　the　PHA　volumetric　productivity　increased　by　27.28%　compared　with　the　control　group.　The　carbon　flux　in　the　pathway　from　acetyl-CoA　to　the　PHA　synthesis　increased　while　the　flux　to　the　TCA　cycle　decreased.　Combined　with　transcriptome　and　proteome　analysis,　the　key　genes　pdhA2,　Paaj,　and　AccA　in　the　PHA　synthesis　pathway　were　up-regulated,　while　gltA　in　the　TCA　cycle　was　down-regulated　under　110　mT　SMF.　This　study　revealed　the　mechanism　of　SMF　enhancement　on　PHA　synthesis　by　H.　mediterranei,　which　provides　an　effective　solution　to　increasing　PHA　volumetric　productivity.　©　2023　Elsevier　B.V.