Facial　expression　synthesis　is　an　important　part　of　the　visual　human-computer　interaction.　In　order　to　establish　a　highly　realistic,　self-adaptive　and　automatic　real-time　facial　expression　synthesis　system,　this　paper　proposes　a　method　based　on　MPEG-4　to　generate　three-dimensional　facial　expression　animation.　The　key　steps　include:　firstly,　mark　some　feature　points　in　three-dimensional　human　faces　and　evaluate　how　these　points　move　from　neutral　to　other　facial　expression　to　get　animation　parameters　of　these　points,　secondly,　calculate　the　motility　factor　of　non-feature　points　in　meshed　human　faces　using　the　interpolation　algorithm　in　this　paper　and　the　animation　parameters　of　feature　points,　lastly,　simulate　the　movements　of　feature　points　along　time　axis　to　realize　facial　expression　animation.　The　finally　synthesized　facial　expression　looks　real　and　natural,　which　confirms　the　validity　of　the　method　proposed　in　this　paper.　©　2011　IEEE.