The importance of collaborative design (CD) to the competitiveness of enterprises has been frequently emphasized. Since CD is highly related to the product development process that involves internal and external organizations, such an environment of a design chain is usually rather complex. Within such a complicated process, soft systems dynamics methodology (SSDM), which consists of soft systems methodology (SSM) and systems dynamics (SD), can be applied to improve the design chain. Product life-cycle cost (PLC) is shown to be an effective measurement to evaluate the performance of a product design process. However, previous literature on SSDM has not been integrated with PLC concept. This study proposes a methodology based on SSDM that evaluates the total cost across different stages of product design in order to optimize a design chain in the CD environment. By integrating PLC into SSDM, the proposed methodology evaluates associated product design activities and minimizes the total costs in order to optimize a design chain.