The huge physical-characteristic differences between air and water would produce complicated impact on
the dynamic environment of trans-media vehicles． In this paper，with the Reynolds number (Re) as reference，the dynamic property of the vehicles crossing different fluids are simulated by using the software CFX to design cases． Simulation results show that there exists a Re inflection point in the flow field during the crossing process，and that，when Re is less than the inflection point，if the Re of the air and the Re of the water are the same，the change trends of aerodynamic parameters and hydrodynamic ones with the attack angle are consistent and their numerical values are similar，and if the Re of the air is close to that of the water，there exists a matching range between flight speed and submerged speed，in which the aerodynamic characteristics are shown to be similar to the hydrodynamic ones． The conclusions can provide a basis for the design of voyage control．