Abstract: Changes of biological metabolism were happened during the seed development of rapeseed. There were gradually increased in activities of glucose-6-phosphate dehydrogenase, isocitrate lyase, isocitrate dehydrogenase and succinate dehydrogenase. The activities of glucose-6-phosphate dehydrogenase and isocitrate lyase increased to maximum ,however,the activities of isocitrate dehydrogenase and succinate dehydrogenase increased slowly when oil synthesized rapidly. During whole developing stages of rapeseed, the glucose-6-phosphate dehydrogenase and isocitrate lyase in different strains with high oil content were more active than with low ones; on the contrary, isocitrate dehydrogenase and succinate dehydrogenase in strains with low oil content were more active than with high ones. The activities of four enzymes in hybrids were expressed between the range of parents.