In recent decades, the product-service system (PSS) has been spotlighted due to its innovation and sustainability. As a novel business system, PSS provides additional value for products through the addition of service, which effectively upgrades the traditional manufacturing industry. For realizing a successful PSS, a robust and reliable operation stage is extremely important for users to stay satisfied and loyal. Thus, designers need to ensure that this system is not sensitive to any influential perturbation. Namely, they must achieve the desensitization of PSS to vulnerability. However, the current PSS design field still does not provide an effective method to assess the vulnerability in the whole life stage of PSS. This would lead to less time for the PSS provider to respond to various events. Furthermore, the tremendous loss could be caused due to the immaturity of the system. Therefore, this research has developed a vulnerability assessment framework based on variation mode and effect analysis (VMEA) for PSS. This developed framework has the ability to identify the potential noise factors and assess their severity based on multiple steps of analysis. This method has proved its effectiveness through an application example, and it is also expected to enable PSS researchers to design a robust PSS.