Waste recycling has,to some extent,a positive effect on solving resource and environmental crises;therefore,it has become an important measure of sustainable development.However,the resource depletion and pollution emissions involved in recycling and manufacturing processes also have negative impacts on nature.To solve this problem,we focused on the waste paper recycling system in order to build an ecological costs model based on material flow analysis,and to provide a basis for optimizing the waste recycling system.In this paper,we define the concepts of ecological costs and sum up the existing researches on these,and ensure that counting ecological costs based on material flow analysis is practical.Ecological costs are cause by resource consumption,waste emissions in the processes of recycling,manufacturing,etc.,and they are divided into the three categories:resource depletion,environmental pollution and protection,and ecological damage.Pollution yield and environmental protection costs are counted by allocating total manufacturing costs into positive and negative products,and then counting resource depletion and ecological damage costs using the LIME method.Total ecological costs in the recycling system are calculated by summing every ecological costs in the whole system.Although ecological cost accounting is an important means of evaluating the ecological load,the constitution of ecological costs for the waste paper system is depicted using the foundation of the material flow chart.The model we built is not only fit for the waste paper recycling system,but also valid for other waste products.In addition,this model counts the ecological costs and finds out the manufacturing progresses with high ecological impacts,thereby improving them and providing the basis for both environmental and economic benefits;thus,it constitutes an efficient waste recycling system.