Based　on　electromechanical　impedance　method,　the　effect　of　load　level　and　defect　degree　on　impedance　spectra　obtained　by　the　PZT　elements　bonded　in　steel　beams　is　investigated.　Different　load　levels　are　simulated　by　applying　mass　on　the　steel　beam　firstly　and　the　influence　of　the　load　level　on　real　impedance　spectra　in　the　frequency　range　of　30-40　kHz　is　analyzed.　Defect　assessment　abilities　by　using　three　different　statistical　methods　are　compared.　It　is　shown　that　Root　Mean　Squared　Deviation　and　Mean　Absolute　Percentage　Deviation　can　characterize　load　level　in　the　steel　beam　very　well.　Based　on　this　research,　circular　hole　defects　are　manufactured　in　steps　to　simulate　different　defect　degrees.　Real　impedance　spectra　in　the　frequency　ranges　of　450-650　kHz　and　770-920　kHz　under　different　defect　degrees　are　obtained.　According　to　corresponding　defect　indices　obtained　by　using　Root　Mean　Squared　Deviation,　it　can　be　found　they　will　increase　along　with　defect　degrees.　The　research　results　show　that　electromechanical　impedance　method　has　a　certain　application　potential　for　health　monitoring　and　quantitative　defect　evaluation　of　beam-like　structures.