Abstract: An algorithm was proposed to analyze the elastoplastic time-history reliability of lateral deformation capacity of aseismatic reinforced concrete(RC) structures on the basis of the improved JC method for calculating the static reliability of structures, the Wilson-θmethod and the member-storymodel. And this algorithm was used for the sensitivity analysis of structural parameters, as random variables, influencing the elastoplastic time-history reliabilityof the story-drift capacityof an aseismatic RC frame. The research result shows that in all the structural parameters, the elastic modulus of concrete and the sectional sizes of beams and columns of an aseismatic RC frame have the greatest effect on its time-history reliability, while as far as some structural parameter is concerned, its effecton the time-historyreliability is changing in the whole process of an earthquake