The　defective　categories　of　port　crane　is　studied　in　details,　based　on　metal　structure　fault　detection,　to　understand　the　actual　status　of　a　port　crane.　First　the　prediction　of　port　crane　life　based　on　Paris　model　is　introduced.　But,　this　traditional　residual　life　prediction　is　not　so　accurate　considering　fracture　mechanics　development.　Then,　the　prediction　model　based　on　grey　system　theory　is　introduced　for　the　study　of　port　crane,　and　a　grey　model　GM(1,1)　of　crack　propagation　is　established.　Next,　a　generic　predict　formula　of　life　prediction　of　port　crane　is　constructed.　Finally,　a　case　study　is　confirmed　that　the　prediction　has　a　good　agreement　with　field　data,　and　its　relative　error　is　less　than　6%,　so　the　proposed　model　has　good　precision　and　forecast　creditability.　©　2011　IEEE.