Marine engine nodular cast iron crankshaft

The present invention discloses a marine engine nodular cast iron crankshaft, which comprises: a main journal arranged on a cylinder, a connection rod neck connected with a connection rod big end hole, and a balance block, wherein rolling fillets are respectively undercut on positions of journal transition fillets formed by the main journal and the connection rod neck with the balance block. The marine engine nodular cast iron crankshaft has the following characteristics that: the structure is simple and reasonable; fillet rolling is adopted to strengthen the crankshaft so as to improve a fatigue strength; and the fillet does not require fine grinding processing after rolling strengthening, and it can be ensured that beating deformation is qualified, such that processing property of the marine engine nodular cast iron crankshaft is better than processing property of the nitrogenization crankshaft, and cost is low.