With the increasing global emphasis on sustainability and the Sustainable Development Goals of the United Nations, improving supply chain sustainability and efficiently distributing orders has become crucial. This chapter introduced the concept of supplier sustainability level in relation to network reliability. In the sustainable supply chain network constructed, a node represents a supplier, assembly plant or customer, and an arc connecting the nodes. For each arc, it has a carrier whose carrying capacity for demand transmission. The capacity of each carrier, indicated by the available delivery containers, should not be considered deterministic, as some containers may be partially reserved by other customers. Under these conditions, such a sustainable supply chain network is regarded as a multi-state sustainable supply chain network (MSSN). The network reliability for an MSSN is defined as the probability that the MSSN can successfully transport a specific amount of goods to a customer under supplier sustainability level and budget. Network reliability is also regarded as a performance indicator for supply chain capability and further helps managers in making decisions.