Gannan pastoral area is not only an important animal husbandry production base in Gansu Province, but also one of the nation's major ethnic concentration areas. In recent years, the increasingly intensified degradation of grasslands in the Gannan pastoral area has been the "bottleneck" factor in restricting grassland animal husbandry and socio-economic development, and in the same time, it has become a very serious eco-environment problem. Therefore, it is important to further examine what might be the best strategy to balance grassland area and livestock number. This should play an important role to maintain the sustainable development in social and economic for the area. In this study, a multi-objective programming approach in Matlab 7.9 software package is used to develop an optimization and management strategy, for the year 2009-2011, in maintaining a balance between forage supply and livestock need in the study area, based on dynamic monitoring data of grassland livestock husbandry and social-economic information before 2009. The purposes of the study are to maintain the balance between forage and livestock and to benefit regional social-economic development while protecting environment. In the study, quantitative changes, in livestock population structure, net increase rate, global increase rate, herd market and slaughter rates, and famers' net income in two different optimization plans (increase or decrease livestock number), are analyzed and compared under five constraints of herd structure optimization, livestock production goal, forage and livestock balance, regional social-economic development, and environmental protection. The results suggest that the strategy of reducing livestock number is a fundamental way to reach our goal. It is found that, in the period of 2009-2011, the optimal percentage of sheep, goats, cattle, horses and mules in the study area should be 68.5%, 6.4%, 25.0%, 0.1% and 0.1%, respectively. This, as compared with the year 2008, is an increase of 11.8% for sheep, a decrease of 1.6%, 8.6%, 1.1% and 0.4% for goats, cattle, horses and mules, respectively. Under condition of grazing throughout an entire year without supplementary feedings, the appropriate stocking rate of natural grasslands in the area is between 2.955-5.029 million su. In recent years, however, overgrazing of natural grassland has been extremely serious in the study area. For instance, it is found that the overloading rate in the study area was up to 72.9% in year 2008, over the maximum carrying capacity of natural grassland, plus supplementary feeding conditions. Grassland and livestock balance is actually a dynamic equilibrium among human being, grassland and livestock, which involves grassland, livestock, eco-environment, socio-economic, and other factors. Based on this study, grassland and livestock balance management in the study area should include: 1) appropriate adjustment of livestock number and type, improvement of breed, and optimization of livestock population structure; 2) increase of livestock supplements by means of adjustment of crop planting area and types, and increase of pasture area; 3) stabilizing areas of natural forest and grassland, and preserving eco-environment in the pastoral area; 4) improving the efficiency of livestock husbandry and market rate of herd; and 5) strictly controlling population growth and enhancing adjustment mechanism of national policy.