Abstract: The modeling and simulation of a condensation system in marine steam power plant were studied by the bondgraph theory. The coexistent mechanical power conversion, heat and mass transfer in the system were analyzed by standard method, and its universal model on the basic physical laws was established. Using practical object to validate the bondgraph model, it is found that the model can preferably respond the static precision and dynamic characteristics of marine steam turbine and has preferable accuracy and realtime characteristic, the conclusions have some theoretic and practical value.