A performance-based seismic design approach for reinforced concrete beam-column joints has been proposed in this paper. Instead of adopting empirical analysis such as in ACI 318M-08 building code, the proposed approach is based on rational analysis of the stress-strain state of the joint. Two limit states are considered in the design: serviceability limit state and life safety limit state. Performances of the joint at these two levels are determined respectively, with due considerations of capacity design philosophy and post-earthquake repair requirements. Then stress/strain analyses of the joint panel using the Mohr circle in conjunction with the softened stress-strain relationship of concrete are adopted simultaneously to design the joint to achieve the predetermined performance level. Effectiveness of proposed method are validated by using the model to interpret the behaviors of joints observed in previous experiments.