The embodiment of the invention provides a marine diesel power system comprising a diesel engine, a conformal heat exchanger with a first inlet and a first outlet thereof connected to the diesel engine and upper and lower sealing heads thereof as well as a second inlet and a second outlet for inflowing and discharging seawater, and a jet device at a second outlet of the conformal heat exchanger, wherein a first inlet, a second inlet and an outlet of the jet device are separately used for sucking seawater discharged from the second outlet, connecting to a diesel engine exhaust tube and discharging seawater and waste gas discharged from the diesel engine exhaust tube. By arranging the jet device at the second outlet, the heat exchange form of the conformal heat exchanger is changed into forced convection heat exchange, so that the heat exchange efficiency of the conformal heat exchanger is improved.