The　quantity　and　morphology　of　spheroidal　graphite　have　an　important　effect　on　the　properties　of　ductile　iron,　and　the　characteristics　of　spheroidal　graphite　are　determined　by　the　solidification　process.　The　aim　of　this　work　is　to　explore　the　precipitation　and　evolution　of　graphite　nodules　in　hypoeutectic,　eutectic,　and　hypereutectic　ductile　irons　by　thermal　analysis,　liquid　quenching　and　metallographic　technique.　Results　show　that　hypoeutectic　ductile　iron　has　the　longest　solidification　time　and　the　lowest　eutectic　temperature;　eutectic　ductile　iron　has　the　shortest　solidification　time;　hypereutectic　ductile　iron　has　the　highest　eutectic　temperature.　After　solidification　is　completed,　hypoeutectic　ductile　iron　has　the　lowest　nodule　count,　nodularity　and　graphite　fraction;　eutectic　ductile　iron　has　the　highest　nodule　count,　nodularity　and　the　smallest　nodule　diameter;　hypereutectic　has　the　highest　nodule　diameter　and　graphite　fraction.　The　nucleation　and　growth　of　graphite　nodules　in　hypereutectic　ductile　iron　starts　before　bulk　eutectic　crystallization　stage,　however,　the　precipitation　and　evolution　of　graphite　nodules　of　hypoeutectic　and　eutectic　ductile　irons　mainly　occur　in　the　eutectic　crystallization　stage.　The　graphite　precipitated　in　eutectic　crystallization　of　hypoeutectic,　eutectic,　and　hypereutectic　ductile　irons,　are　61％,　68％　and　43％　of　total　graphite　volume　fraction,　respectively.　Simultaneously,　there　are　plenty　of　austenite　dendrites　in　hypoeutectic　and　hypereutectic　ductile　irons,　which　are　prone　to　shrinkage　defects.　Therefore,　the　eutectic　ductile　iron　has　the　smallest　shrinkage　tendency.