Abstract: Influence factors and proper value of the equivalently distributed stiffness coefficient of diaphragm wall in the method of vertical beam on elastic foundation in the structural design of circular diaphragm wall are discussed. The influences of joint numbers of circular diaphragm wall, pit mud in groove segment, three joint types (namely, flexible joint, semi-rigid joint and rigid joint) and load bias range on are studied. The results show that joint numbers of the circular diaphragm wall and pit mud in the groove segment have little influence on , but the joint stiffness and load bias range affect it strongly. In addition, the specified value of ranging from 0.5 to 0.7 in the regulation seems to be appropriate for the diaphragm wall with semi-rigid joint, but a little surplus for the rigid joint and a little lower for the flexible joint. The proper value of should be taken through a comprehensive analysis of the stress state of the joint and appropriate calculation analysis.