Design resources such as design tools, knowledge, and data play important roles in the product variant design. The requirements for these resources as well as the resource integration mechanisms are evolving along the life-cycle based product design process. It is expected by designers that not only right design resources but also appropriate integration methods can be found and applied timely to realize design variations efficiently and effectively. In this paper, a hybrid design resource integration framework is proposed based on the design process and resource modeling in order to satisfy the evolutionary requirements for design resources in the process. The integration framework is divided into two levels, namely the abstract integration of virtual resource classes into task templates in the design process modeling and the concrete integration of resource instances into design activities in the design project runs. Based on the two-level integration framework, a hybrid integration mechanism including flexible and stiff integration models and three integration transition methods is proposed to adapt to the from-abstract-to-concrete design evolution process. The system structure and behavior models are given, according to the analysis of integration framework. A hypo-pneumatic spring design case is used to demonstrate the utility of the hybrid integration system. Design results obtained based on the resource integration tool and the traditional manual design approach are compared to assess the tool performance, which shows substantive improvements of design efficiency and efficacy.