Abstract:Material metabolism planning model based on the framework of material flow analysis(MFA) and three dimensional physical input-output table(PIOT) is a powerful tool for circular economy planning. In the real economic system, the problem of products measured in different units in a same industry causes great trouble to build the material metabolism planning model. Negative input method was used to solve this problem. Firstly, the feasibility of the negative input method was discussed theoretically. Secondly, practical ways of using the negative input method to solve the above problem under the framework of three dimensional PIOT was afforded. Finally, the method was verified in the case study of circular economy planning in Yima City. The negative input method could also reflect the technical relationship between main products and byproducts in PIOT, while the shortcomings in monetary input-out table (MIOT) could be overcome in PIOT. In practice, the bias between the negative input amount calculated by the row model of input-output analysis and the real total demand should be treated properly. The relationship between the demand amount and supply amount of byproducts should also be handled properly. The case study showed that the method is feasible and practicable.