The　fatigue　crack　propagation　process　of　specimen　made　from　Q345R　was　monitored　by　acoustic　emission　(AE)　equipment.　The　AE　characteristic　of　the　specimen　generated　during　the　fatigue　crack　propagation　was　obtained　by　parameter　analysis　method　and　wavelet　transform　method.The　results　show　that　the　fatigue　crack　growth　curve　comprises　four　phases　of　the　crack　generation　phase,　the　low-speed　crack　propagation　phase,　the　high-speed　crack　propagation　phase　and　the　fracture　phase,　and　the　variation　of　signal　parameters　presents　the　similar　tendency　to　the　fatigue　crack　growth　rate.　The　values　of　signal　parameters,　such　as　count,　energy,　and　amplitude,　are　stable　and　low　in　the　crack　generation　phase　and　low-speed　crack　propagation　phase,　and　relatively　unstable　and　high　in　the　high-speed　crack　propagation　phase　and　fracture　phase.　The　type　of　signals　is　burst　emission　and　the　frequency　ranges　from　100kHz　to　180kHz.　From　these　correlations,　it　may　be　possible　to　predict　the　remaining　service　life　of　a　pressure　vessel　from　the　results　of　short-term　AE　monitoring　of　crack　propagation.