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.