The　performance　degradation　of　12CrMoV　steel　generally　occurs　under　a　long-term　working　period　in　a　hightemperature　environment.　In　order　to　improve　the　reliability　of　a　single　nondestructive　testing　method　for　the　performance　degradation　analysis　of　12CrMoV　steel,　an　advanced　magneto-acoustic　compound　inspection　method,　in　which　pulsed　eddy　current　(PEC)　and　ultrasonic　waves　were　obtained　from　a　single　electromagnetic　acoustic　transducer　(EMAT)　testing　signal,　was　adopted.　The　magneto-acoustic　compound　inspection　method　was　carried　out　on　12CrMoV　steel　plates　heat-treated　at　different　temperatures　and　times.　New　parameters,　including　the　slope　and　peak　value　of　PEC,　and　the　amplitude　and　attenuation　of　ultrasonic　waves,　were　introduced　to　evaluate　the　performance　degradation　of　12CrMoV　steel.　It　was　found　that　ultrasonic　waves　manifested　higher　sensitivity　than　eddy　current　when　the　microstructure　changed　significantly.　Therefore,　the　magneto-acoustic　compound　inspection　method　is　advantageous　for　evaluating　the　performance　degradation　of　12CrMoV　steel.