An accelerating calculation of reliability analysis on strength and stiffness for frame structure was derived. The method of numerical analysis was combined with recurrence formula, to generatelimit state function of continual variational structure. This methodcan simplify the algorithm for identifying systemic dominant failure modes, because the repeated assembly of global stiffness matrix and repeated inverse matrix operation in analysis are avoided. A new criterion of degenerating the structure into mechanism is introduced. Continual analysis of variational structure can be realized.