Abstract: In order to efficiently obtain the equal load carrying capacity (ELCC) joint shape parameters of joint with different defects,an ELCC design system of joint based on stress intensity factor was developed by combining fracture mechanics theory and expert system. The results show that ELCC joint shape parameters of joint with different defects could be efficiently obtained using this system. The efficiency and accuracy of ELCC joint design could be obviously improved,and the ELCC design method could also be extended. Stress intensity factor,J-integral, crack tip opening displacement,critical stress and critical crack length of defected joint under static load could be obtained with this system. The allowable load amplitude,crack growth rate and other corresponding parameters of defected joint under fatigue load could also be obtained with this system. This system can guide the joint shape design and safety assessment.