In order to study the influence of joint stiffness on the stability of tubular truss arch, a variable stiffness spring model under reciprocating load was used to replace shell element to consider the semi-rigidity of joints on the basis of the consistency of hysteretic performance of spring element and shell element. The stiffness equation of the spring model is determined by the skeleton curve of the node shell element model under reciprocating load. Taking a tube truss arch with a span of 50m and a span of 0.29 as an example, the stability of the joint domain spring model and the common model is analyzed by using material and geometric nonlinear finite element method. The results show that "static instability mode" is the most unfavorable initial defect form of space tube truss arch. The influence degree of joint stiffness on the bearing capacity of tubular truss arch is related to the size, distribution form and load range of initial defects.