Abstract: The caryopsis development and the accumulation of starch, protein, soluble sugar and fat in waxy corn were studied by routine methods. The development of starch granule was observed by scan electric microscope. Waxy corn was harvested at 25~30 days after pollination suitably. Starch content increased rapidly at early period and slowly from 20 days after pollination. Protein content decreased rapidly and then increased slowly. Soluble sugar content increased and then decreased. Fat content showed a rise tendency as a whole. Fresh weight was positively correlated to starch content(r=0.915**) and negatively correlated to protein content(r=-0.961**). starch content was negatively correlated to protein content(r=-0.985**). Starch granule of cutin endosperm arranged tightly and showed a “football” shape. Starch granule of powder endosperm arranged loosely and showed a polyhedron shape.