Abstract: Corn is the most important energy feed for ruminant. The main component of corn is starch and its content is 64%-78%. Starch is easy to be digested and absorbed, with high efficiency. Especially the corn after steam-flaked treatment could regulate the degradation of starch in different digestion organs of ruminant and further enhance its nutritional value. In order to study the nutritional values of steam-flaked corn, granule corn and their TMR diet, the gas production in vitro and fermentation parameters of steam-flaked corn, granule corn and their TMR diet were determined by using gas production in vitro method. The results showed that corn after steam-flaked treatment could effectively improve its degradation rate in the rumen of ruminant and significantly enhance its nutritional value.