An　ideal　engineering　computational　environment　for　solving　design　problems　should　be　flexible,　which　is　characterized　by　helping　designers　to　establish　solution　strategy　conveniently　and　integrating　design　resources　effectively.　In　this　paper,　a　flexible　engineering　computational　system　called　Engineering　Computational　Service　Grid　(ECSG)　based　on　Grid　portal　technology　and　workflow　technology　is　presented,　and　the　architecture　of　ECSG　is　described　detailedly.　For　managing　solution　strategy　of　engineering　computational　job,　the　structure　of　BPEL　(Business　Process　Execution　Language)　based　workflow　management　subsystem　is　put　forward,　and　an　application　scenario　of　ECSG　is　given.　The　research　results　aforementioned　can　clarify　the　functional　system　of　engineering　computational　environment　and　provide　an　approach　to　constructing　flexible　engineering　computational　environment.　©　2008　IEEE.