Abstract: Three-dimensional visco-elastic artificial boundaries in time domain are developed by means of theory of elastic wave motion in this paper. Three-dimensional visco-elastic artificial boundary equations along normal and tangent directions are derived based on three-dimensional wave motion equations. Numerical simulation techniques of visco-elastic artificial boundaries in time domain are studied. Numerical examples of classic wave motion problems demonstrate that high precision is achieved by use of three-dimensional visco-elastic boundaries, and that the boundaries can be used in analysis of three-dimensional wave motion problems easily.