In order to study the impact of the defect rate on different parameters in buyback contract, the product defect
rate is incorporated into the buyback contract, and the product defect rate and coordination parameters are regarded as
fuzzy number too. Then a supply chain fuzzy buyback contract based on the context of unrepairable defect is built by
using function principle and graded mean integration representation, and the feasibility of the fuzzy buyback contract is
investigated. Numerical analysis shows that the impact of defect rate on different parameters in buyback contract is different.
Building a fuzzy buyback contract is an effective and feasible method when decision-makers do not have information on
product defect rate and there are differences between suppliers and retailers for coordination parameters.