Fatigue　crack　growth　rates　(FCGRs)　of　X70　pipeline　steel　base　metal　(BM)　and　heat　affected　zone　(HAZ)　were　studied　in　the　hydrogen　sulphide　environment.　X-ray　diffraction　method　was　used　to　measure　the　residual　stress　of　BM　and　HAZ.　Modified　wedge　open　loaded　specimen　was　selected　for　the　test　in　the　simulated　actual　working　conditions.　In　the　saturated　H2S　environment,　the　crack　growth　experiments　were　carried　out　under　low　frequency　(f=0.01　Hz)　and　three　stress　ratios　(R=0.7,　0.8　and　0.9).　Results　showed　that　there　was　obvious　residual　tensile　stress　in　HAZ.　The　presence　of　H2S　greatly　accelerated　the　FCGR.　With　rising　stress　ratio,　crack　closure　effect　weakened,　and　then　the　increasing　degree　of　hydrogen　embrittlement　of　the　crack　tip　leads　to　FCGR　acceleration.　Microstructure　defects,　inclusions　and　high　residual　tensile　stress　of　HAZ　made　the　FCGR　of　this　area　higher　than　the　FCGR　of　BM.　Scanning　electron　microscopy　scans　of　the　fracture　suggested　that　the　fracture　mode　of　the　corrosion　fatigue　of　the　X70　material　belonged　to　brittle　fracture.　Cleavage　fracture　was　the　dominant　form.　The　differences　between　corrosion　fatigue　fracture　morphologies　of　BM　and　HAZ　were　not　very　large,　and　the　relief　of　the　fracture　of　HAZ　was　larger　and　the　cracks　longer.