In　the　prevention　and　rehabilitation　stage　of　low　back　diseases,　it　is　necessary　to　detect　the　state　of　muscles　to　avoid　excessive　fatigue　and　injury　caused　by　continuous　exertion　of　lumbar　muscles.　In　this　paper,　an　in　vivo　experimental　platform　for　measuring　low　back　muscle　impedance　was　established　in　order　to　detect　the　different　force　states　of　muscle　and　study　the　corresponding　relationship　between　muscle　force　state　and　muscle　impedance.　In　the　experiment,　Biering-Sorensen　(BS)　test　was　used　to　make　the　low　back　muscle　contract　continuously,　and　different　weights　(5　kg,　2.5　kg,　0　kg)　were　used　to　distinguish　the　force　state　of　muscle.　The　impedance　analyzer　was　used　to　measure　the　muscle　impedance　parameters　under　different　load　in　the　subject＇s　low　back　muscle　for　studying　the　electrical　impedance　characteristics　of　different　low　back　muscle　states.　The　results　showed　that　the　relative　resistance　R＇　of　EIM　was　a　downward　trend　with　time　and　the　5　kg　load　had　the　fastest　decline;　The　relative　reactance　X-c＇　of　EIM　was　an　upward　trend　with　time,　the　5　kg　load　also　had　the　fastest　rise.　The　slope　k　of　the　fitting　curve　of　R＇　and　X-c＇　were-5.8　x　10(-4)　and　8.76　x　10(-4)　respectively.　Therefore,　EIM　can　effectively　detect　the　state　of　low　back　muscles.