The rationality of Early Supplier Involvement (ESI) in product development has been well recognized in terms of transforming supply chains into integrated value systems. Despite past advancements in ESI, some of the unique issues have not been addressed for ESI in e-product configuration for mass customization. As far as variety management and online configuration are concerned, the difficulties of ESI in online mass customization manifest themselves through two main aspects: (1) mass customization is facing a variety dilemma resulting from the continuous generation of product variants to meet diverse customer needs. (2) Online configuration is another crucial factor to the success of electronic product configuration. Towards this end, this paper discusses critical issues of ESI for online production customization and accordingly outlines a technical framework.