Conceptual design plays a pivotal role in generating creative design solutions and, in most cases, reuse of existing design knowledge is necessary. However, lack of a consistent design knowledge representation model and neglect of an integrated approach to support various formats of design knowledge reuse constrain conceptual design from transforming design requirements into practical promising design solutions. In order to solve these problems, this paper presents a constrained function-behavior-structure knowledge cell (CFBS) model to provide conceptual design process with a consistent knowledge representation model. CFBS-based integrated approach for design knowledge reuse is proposed, which includes three-level CFBS retrieval process to obtain most relevant CFBS expressed in various types, three-stage design synthesis process to produce suggested design solutions, and evaluation process to select the most feasible design solutions. The effectiveness of the proposed design process was illustrated with conceptual design of the micro-feed drive module of insulin pump based on the CFBS library.