The Qinghai-Tibetan Plateau is a large and elevated plateau (mean elevation 4500 m) in northwestern China, where with a harsh environment for animal survival. Tibetan sheep is an important dominant livestock that inhabit this harsh environment. The objective of this trial was to preliminarily explore and compare the effects of indigenous barley straw (BS) and artificial cultivated oat hay (OH) on growth performance, visceral organ mass and meat quality of Tibetan sheep. Twenty-four Tibetan sheep with initial weights of 15.9±1.92 kg were randomly assigned to two mixed diets containing the same concentrate mixed with BS or OH, and the experiment was carried out in a completely randomized design. The weight of lungs and thymus for OH was greater (P≤0.05) than that of BS, while the weight of other viscera (heart, liver, kidney, epinephros and spleen) had no significant difference (P>0.05) between the two. The weight of the rumen, reticulum and abomasum for OH was 10.31%, 31.22% and 33.44% (P≤0.01) higher than that of BS. The length of the colon in sheep fed OH diet was longer (P≤0.01) than the sheep fed BS diet. The content of Histidine in longissimus dorsi muscle of OH was greater (P≤0.05) than that of BS, while there were no significant (P>0.05) differences between the two for the other individual amino acids (AA), umami AA, essential AA and total AA. It is concluded that the two types of roughage did not affect the growth and slaughter performance, meat quality, but OH is beneficial for the gastrointestinal development for Tibetan sheep.