We investigated the fatigue crack propagation of base metal, weld metal and heat attected zone in 316L stainless steel. And we analysed acoustic emission signals during the fatigue test by time-frequency analysis method. The specimens of weld metal and HAZ had longer fatigue life and slower rate of crack propagation better than base metal. And as a result of time-frequency was 200-300 kHz was obtained by fatigue crack propagation and 500 kHz was obtained by dimple and separate of inclusion.