The　service　life　and　structural　safety　of　components　are　affected　by　the　thermal　ageing　of　materials;　therefore,　a　non-destructive　evaluation　of　materials　is　extremely　essential　and　crucial.　In　this　work,　heat-resistant　steel　Cr12MoV　was　selected　as　a　specimen,　and　the　embrittlement　period　of　heat-resistant　steel　Cr12MoV　was　obtained　by　accelerated　thermal　ageing　experiments.　The　effects　of　service　temperature　and　service　time　on　the　mechanical　properties　of　heat-resistant　steel　were　analysed.　The　non-destructive　testing　of　heat-resistant　steel　was　carried　out　by　using　magneto-acoustic　compound　detection　techniques　based　on　electromagnetic　acoustic　transducers.　In　the　process,　magneto-acoustic　compound　detection　signals　were　decoupled.　The　electromagnetic　characteristic　parameters　and　ultrasonic　characteristic　parameters　of　the　detection　signals　were　extracted　to　evaluate　the　mechanical　properties　and　thermal　ageing　of　heat-resistant　steel.　The　quantitative　evaluation　ability　of　thermal　ageing　brittleness　of　heat-resistant　steel　was　improved　by　using　the　magneto-acoustic　compound　detection　techniques　compared　with　single　eddy　current　detection　method　or　single　ultrasonic　detection　method.