The　simulation　of　large　crowd　of　characters　plays　an　important　role　in　real-time　application　such　as　games　and　simulation　systems.　This　kind　of　applications　can　provide　an　immersive　feeling　of　life　into　the　virtual　environment,　but　it　requires　a　great　mount　of　computational　power.　To　increase　the　efficiency　for　this　simulation,　we　propose　a　GPU-based　crowd　simulation　method.　We　present　a　novel　unified　interaction　framework　for　both　interactions　in　virtual　environment　and　user＇s　input.　We　also　present　a　new　crowd　rendering　method.　The　results　validate　that　the　presented　method　makes　tradeoff　between　CPU　and　GPU,　and　can　get　interactive　frame　rate　while　simulating　large　crowd　of　characters.　1548-7741/Copyright　©　2008　Binary　Information　Press　October　2008.