In　recent　years,　polychromatic　sets　have　emerged　as　a　promising　approach　for　simulation　modeling.　The　theory,　techniques　and　approaches　of　polychromatic　sets　can　play　an　important　role　in　product　life-cycle　simulation,　product　conceptual　design,　concurrent　engineering,　and　virtual　manufacturing　for　product　modeling,　process　modeling,　and　process　optimization.　In　this　paper,　the　concept　of　polychromatic　sets　is　introduced.　After　discussing　the　concept　of　polychromatic　sets,　the　mathematical　aspects　of　the　theory　and　the　relationship　between　the　unified　pigmentation　and　individual　pigmentation　is　discussed.　An　application　example　is　also　given　in　the　paper.　(C)　2002　Published　by　Elsevier　Science　Ltd.