Based　on　the　fact　that　information　technology　diffusion　(ITD)　can　generate　tremendous　pulling　function　on　the　growth　of　GDP　and　economic　development　pattern,　this　article,　from　the　perspective　of　diffusion　of　information　technology,　aims　to　estimate　and　contrast　the　contribution　rate　to　nominal　GDP　and　real　GDP　by　information　technology　diffusion,　through　eco-analysis　of　regression　model　involved　in　capital,　labor,　technology　and　GDP.　In　addition,　this　paper　aims　to　estimate　the　impact　level　of　information　technology　on　GDP　backed　by　the　analysis　of　time-series　data,　thus　come　to　the　conclusion　that　information　technology　industry　is　always　taking　the　role　of　＇accelerator＇　and　＇catalyst＇　to　economic　growth.　©　2011　IEEE.