In order to improve the pastoral areas of the Tibetan alpine forage yield, ease the contradiction between the pasture and livestock. The study was to assess the different mixed proportion of seeding grass between ‘White oats No.2’ and Vetch in Lhasa of Tibet, was to carry out the comparative study of forages in appropriate cutting time. The results of the proportion of mixed seeding showed significant difference among plant yield, protein, fat, crude fiber, crude ash, Ca and P content and it significantly improved the plant yield and forage quality; also with the increase of the proportion of the Vetch, protein content increased too. The highest content of Unicast vetch reaches 22.58%. The optimal mixed seeding proportion was H4, Fresh yield reaches 7.71 kg/m2, protein content reaches 13.66%, fat content reaches 1.99%, crude fiber content reaches 35.99%, crude ash content reaches 6.77%, Ca:P 5.36. Thus, ‘White oats No.2’ and Vetch could be promoted according to the above proportion (Vetch 40%+ White oats No.2 60%) in the favorable climate region in Tibet, in order to improve the quality of forage grass.