There　is　a　big　error　in　the　economic　prediction　of　port　and　marine　engineering,　based　on　the　grey　theory,　the　economic　prediction　method　of　port　and　ocean　engineering　is　put　forward.　Therefore,　a　method　of　economic　prediction　of　port　and　ocean　engineering　based　on　grey　theory　is　designed.　First,　the　index　system　of　economic　association　analysis　between　port　and　ocean　engineering　is　established,　then　calculate　the　whole　interval　value　with　NPV,　to　evaluate　the　economy　of　port　and　ocean　engineering,　at　last,　the　prediction　of　port　and　ocean　engineering　economy　is　completed　by　using　grey　theory　method.　Experimental　comparison,　the　prediction　error　of　this　design　prediction　method　is　small,　after　repeated　training　of　multiple　samples,　and　correct　the　weight　coefficient　in　the　direction　of　reducing　the　error,　satisfactory　results　obtained,　so　as　to　reduce　the　error　of　economic　forecast　of　port　and　ocean　engineering,　it　has　certain　practical　significance.