The　fault　diagnosis　method　of　VLSI　based　on　infrared　imaging　scan　technique　is　described.　During　integrate　circuit　working,　the　power　supply　dissipation　from　each　part　is　regarded　as　fault　information,　the　fault　feature　extraction　is　completed　by　infrared　imaging　acquiring　and　imaging　processing,　the　fault　pattern　classification　is　realized　by　neurons　network.　The　method　can　solve　the　fault　diagnosis　problem　of　very　large　scale　integrate　circuit　with　power　dissipation.　The　results　show　that　the　diagnosis　method　is　feasible.