Fracture　characteristics　of　X70　pipeline　steel　with　surface　crack　were　investigated　by　three　point　bending　tests　of　center　surface　crack　specimens.　The　experiment　results　indicate　that　two　dimension　fracture　mechanics　parameters　KI　can　not　characterized　factually　for　experiment　phenomenon　and　crack　tip　stress　intension　of　surface　crack.　Three-dimensional　fracture　mechanics　parameter　KZ　was　proposed　to　characterize　the　crack　tip　stress　intension　of　surface　crack.　Three-dimensional　fracture　toughness　KZC　does　not　regard　geometry　size　and　shape　of　surface　crack,　and　it　is　a　objective　toughness　of　pipeline　steel　with　surface　crack.　The　unified　fracture　criterion　of　through　thickness　crack　and　surface　crack,　KZ　=　K√F(TZ)　≤　KZC　was　constructed.　Combining　with　failure　assessment　diagram　(FAD)　technology,　this　3-D　fracture　mechanics　criterion　can　be　used　to　evaluate　the　safety　of　pipeline　containing　surface　crack　or　surface　crack-like　flaw.