Abstract: In order to improve the efficiency of the collision detection for two convex polytopes,this paper proposes a fast projection-separation approach.It respectively constructs quasi projection-separation facet sets of two convex polytopes while their orthogonal projection on the centerline overlap mutually.Afterward it judges the separation of two convex polytopes by confirming non-overlap in orthographic projection on the centerline or by finding out a projection-separation facet from two quasi projection-separation facet sets,otherwise a collision is judged.This approach speeds up the intersecting detection by orderly judging alternately whether every facet of two quasi projection-separation facet sets is projection-separation facet or intersecting one.Complexity analysis and numeric experiments show that its average detection efficiency is superior to existing algorithms.