Abstract: Abstract: Grassland is the largest terrestrial ecosystem in China. In recent years, climate change and human activities have seriously degenerated the grassland ecosystem. Therefore, how to maintain the sustainable development of grassland ecosystem has aroused great concern in the world. This study aimed to optimize water and land resources allocation in pastoral areas and determine reasonably the developmental scale of water, land and grass resources and carrying capacity of livestock so as to maintain the sustainable development between resources and livestock depending on the self recovering nature of the natural grassland ecosystem. A water and land allocation model related to water-land-forage-livestock arrangement for grazing areas was proposed on the basis of their conditions and challenges. The premise of this model was the healthy development of grassland ecosystem. The total amount of water consumption in the region determined by the strictest water resources management system was selected as the control index. The bottom line of the model was the carrying capacity of water, land and grassland resources. The criterion of this model was the balance among water, land, forage and livestock. According to this model, water and land resources in pastoral areas could be reasonably allocated. The appropriate scale of agriculture and husbandry could also be determined. The water and land resources allocation model was constructed by the multi-objective programming method. The genetic algorithm (GA) evaluating individual fitness based on target sorting matrix was used to solve the model, and FORTRAN language was used for programming and data processing. Results of the model showed that the suitable appropriate irrigation area in the pastoral area for agriculture and husbandry was 9.361 million hm2 in 2030, and the corresponding suitable amount of livestock was 288 million sheep units. Under coupled irrigation and application of artificial and natural grasslands, the overall balance of forage and livestock for rangeland would be achieved in 2020, but there was an imbalance among regions, and the balance of forage and livestock would be completely achieved in 2030. With the area of artificially irrigated grassland was increased, the level of supplementary feeding of livestock would be improved. But by the condition of water resources, the feeding level of livestock in all the regions did not reach barn feeding level. The balance between the development and utilization of rangeland could be achieved in 2030. Thus, the allocation model of water, land, forage and livestock will provide a new approach for maintaining the sustainable development of grassland ecosystem as well as sustainable social and economic development in the pastoral areas.