Based on the knowledge of panel method, which has been used widely in ship hydrodynamics. This paper illuminates deficiency about Kutta condition of theoretical value and numerical value respectively according to physical facticity of Kutta trailing edge condition. Calculation model of hydrodynamic three-dimensional short foil is established according to a mount of experiments. The effects of tip vortex and decay of vortex panel strength can be successfully taken in account in the model.The hydrodynamic performance and the calculation of induced velocity along flow on the constant point after foil shows that if the effects of tip vortex and decay of vortex panel strength be considered, the accuracy of calculation can be increased. Velocity peak value in propeller wake current and distribution of induced velocity after three-dimensional short foil else can be calculated accurately. This calculation model is more approximate to experimental value than general panel method such as hydrodynamic performance and induced velocity after airfoil.In terms of this new model of computational hydrodynamics, the paper calculates distribution of induced velocity about propeller researched in detail, induced velocity of propeller caused in random point can else change periodically, even under constant situation when propeller rotates in underwater. This kind of change has complex relationship to geometry of propeller, flow velocity and load. However it can be testified through computation that induced velocity produced by propeller on the points far from trail vortex change according to sine. So average induced velocity along circumference can be calculated easily, as long as the induced velocity of two random points far from 1/2 periodicity can be attained. A lot of time for calculation of disturbance between multi-propellers and multi-rudders can be saved according to the conclusion.In this paper, effect caused between propellers and rudders can be taken into consideration through iteration. Disturbance between single propeller and single rudder else can be calculated. The result according to the way in this paper is identical with experimental value very well which is calculated in the inland boat institute of Germany. Finally ,the location parameters of four- propellers and two rudders propulsion system on certain great ship have been calculated ,effect of propulsive performance of each location parameter can be known in this way.