Abstract: Since the end of the 20th century，large-scale ecological construction policies has been implemented in China and the subsequent performance evaluation of the policies is an important issue which is worthy of deeper inquiry. The current performance evaluation of ecological construction policies rarely involves the government，farmers and other behavior subjects in relation to their course of action regarding the eco-construction process，even it is unable to explain the crucial issues such as whether ecological construction process is fair，how governance efficiency is and whether the ecological result is sustainable. Firstly，this paper starts from analyzing the physical mechanisms of desertification，it offers a word of policy index [PIX] and with which to indicate the effect that ecological construction policies have had on desertification，then the policy index is decomposed into two variables，which are spatial span PSS and time intensity PEF，PIX=（PSS+PEF）/2. Taking the grassland grazing prohibition policy in Yanchi County of Ningxia as an example to calculate the relevant coefficient of the grass grazing prohibition policy and desertification change and a score was obtained with -0.746，indicating that it has got through the significant α=0.01 inspection and the grassland grazing prohibition policy and the desertification area reduction related significantly. Secondly the project takes the public value as a basic framework to build a system which combines the execution process of desertification control policy and the performance evaluation of the ecological effects，then a quantitative evaluation was made on the performance of the desertification control policy through extracting the index factors from some aspects such as the “fairness” of the policy process，respect for the subject of “co-production”，the management “efficiency” of the government departments，the “sustainability” of ecological effects and the relevance of ecological policy on desertification change and so on. By using analytic hierarchy process （AHP） method to calculate the weight of each index factor，the quantitatively measured results were obtained，knowing that the grassland grazing prohibition policy in Yanchi County，Ningxia Province，China has poor effect with public value performance score of 0.378 3. Seen from the desertification control effect，the grass grazing prohibition policy has achieved the ecological goals of controlling desertification，but it does not consider the farmers’ ecological compensation and participation will，so it not only damaged the enthusiasm of farmers and herdsmen in the ecological construction but also brought serious challenges on the sustainability of grazing prohibition results. It is evident that the desertification control policy is a good policy only when it runs on the limited track with public value and plays a significant role in the desertification control. The performance evaluation indexes and models of the desertification control policy based on public value offered in this project are of great significance and feasible. This paper will provide a new and scientific method for the performance evaluation of ecological construction policy and a new attempt to incorporate the ecological construction policy into the government performance management system. It also provides a value case to evaluate the performance of government’s ecological construction policies from the perspective of public value on the project level.

Key words: ecological policy, public value, performance evaluation, desertification