Abstract: The wave radiation effect of infinite fluid medium is an important factor affecting the dynamic response of sea area engineering. Artificial boundary is an effective method to realize the numerical analysis of near-field wave motions in such open systems. In this paper, the dynamic artificial boundaries of open domain fluid medium are deduced based on the theory of fluid wave motions in displacement scheme. The dynamic artificial boundary conditions of wave motions in one-dimensional, two-dimensional and three-dimensional fluid media are formed respectively. As a result, the dynamic artificial boundary of plane wave in one-dimensional fluid medium is classical viscous boundary. On the two-dimensional artificial boundary of cylindrical wave and three-dimensional artificial boundary of spherical wave, the nodal stress is proportional to the speed and acceleration of the node. Therefore, the boundary conditions of these two dimensions can be equivalent to the artificial boundaries composed of the damping-mass system. Furthermore, the corresponding numerical simulation techniques of the fluid medium dynamic artificial boundaries proposed in this paper are discussed, and the realization methods on ANSYS platform are given. Examples of the near-field dynamic response problems show that, for the simulation of the transmission and absorption of the axisymmetric and the non-axisymmetric wave motions. in fluid medium, the calculation accuracies of the dynamic artificial boundaries proposed in this paper are relatively high. The reliability and practicality of those artificial boundaries are verified. The artificial boundaries of fluid medium developed in this paper can be combined with large commercial finite element software, which can provide some insight in the dynamic analysis methods of sea area engineering including sea area terrains and islands.