Tibet autonomous region is one of the main pasturing areas in China，with all area of the grass lands of 8.205 19 m·hm2 which accounts for 68.1％ of the total territory area in Tibet and 20％ of the total grass land in China．The grass lands of Tibet autonomous region is one of the main resources，and has an important standing to social economic development of Tibet，and is also an important ecological protective screen for the Southwest region in China．There are some degradation phenomena in the grass lands and areas of the degraded grass lands have been increased，because ecological environment is very fragile，and unreasonable grass land uses by man are strong and global climate is
being changed．It is fount that the degraded glass lands．of Shen Za county in 1986 accounts for 31.6％ of thp whole  county land area．and is iTInteased to 75.54％ in 2000．

The features of the degraded grass lands ale as follows：the height of the glass community is decreased，cover rate and yield of the grasses are also decreased，dominant species of the grass communities are being changed，and harmfulness of poisonous weeds and rats have become more and more serious.

In paper six prevention countermeasures ale suggested：1．To change ideas，and to set up guiding ideology that lays egual stress on both livestoeks and grasses；2．To strengthen administrative organization construction，and to manage the grass lands by the government laws；3．To stabilize use right of the grass lands，and to prefect contracting responsibility system for grass and livestocks；4．To realize transform of animal husbandry of the grass lands from quantitative type to qualitative type and benefit type；5．To adjust livestock structure，and to make reasonable distribution of the livestocks；6．To strengthen basis research and deVeloninz resealch of the animal husbandry.