Present paper intents to provide a three dimensional circulation model which is universally applicable for continental shelf. The governing equations which are the three-dimensional, time-dependent and free surface, nonlinear Navier-Stokes equations are transformed into α,β,σ, t^* coordinate system for increasing the resolution in vertical direction in shallow region and are solved together with their boundary conditions by finite difference technique. A space staggered grid system is employed for computation. For computational effeciency the model makes use of the concept on process-splitting which partition the fluid flow into two parts, and whereby the volume transport and vertical velocity shear are solved separately, The fast moving external gravity waves are treated by semi-implicit scheme (ADI )for advantage of great time-step and computational stability. An implicit scheme in vertical direction with leapfrog difference in time stepping is used to calculate the slow moving internal gravity waves. The finite difference equations can be demonstrated to by of second order accuracy in space and in time. The model has a good computational stability.To illustrate the application of present model to continental shelf sea, the tidal current in the Bohai Sea is computed. A good agreement of the computed results to the observed is achieved.