The effects of pretreatment process on the micro-structure of rapeseed and the presence state of rapeseed oil in cells were researched. The cell ultra-structures of rapeseed after flaking, cooking, expanding and pressing were analyzed by transmission electron microscope (TEM). Rapeseed cell was extruded obviously by flaking process and it turned from circle shape to ellipse shape. After flaking the cell wall was partly broken and a few lipid droplets were gathered together. A few cell wall was destroyed and some lipid droplets came closely and agglomerated into larger particles by cooking. Cell wall was destroyed totally and the cytoplasm was extruded out by expanding. Most lipid droplets came close enough to agglomerate into larger particles and fully leaked out by expanding. The shape and structure of rapeseed cell were devastated by pressing. It was showed that expanding was more suitable for broking the structure of the cell than cooking and it would be the best way for oil making.