Abstract: To analyze the nutritional quality variation of Rong Chang pigs at different growth period( newly born pigs and 25,50,90,150,240,300 days old). 15 pigs at every periods were selected and contents of moisture,crude protein,delicious amino acids( aspartic acid,glutamic acid,alanine,glycine,arginine),crude fat,essential fatty acids( linoleic and linolenic) were measured and analyzed. The results showed that,change trend of moisture,crude protein,delicious amino acids,crude fat,essential fatty acids were regularity with the days increasing. The stage from birth to 50 days was the important stage in which crude protein was increased significantly( p < 0.05),and delicious amino acids,crude fat,essential fatty acids were also at the high level.The stage at 50~150 days was the stage in which crude fat and essential fatty acids were at lower level.The period from 150 to 240 days old were the other critical period of the increasing of crude fat,essential fatty acids and the formation of characteristic flavor of Rong Chang pigs.