This paper presents Integrated Cooperative Time-variation System (ICTS) and its application for constructional process of complex steel structures. ICTS is based on integrated model comprised of structures, boundary conditions, loads, material properties, construction facilities, where all those are supposed to be time-variation associated with a complex construction process. ICTS can deal with mainly time-variation analysis of construction processes, including pre-set deforming, integrated lifting, temporary support removal, rotation pulling, sliding and tensioning. Besides, several key control technologies of structural force and configuration during structure construction process are introduced, such as obtaining error criteria of cable’s length in tensile structures, controlling influence of constructional environmental temperature, estimating differences between internal and external tubes’ vertical deformation of skyscrapers due to shrinkage and creep of concrete of internal tube, evaluating residual internal force of complex welding structures. ICTS and these key control technologies reinforce traditional construction analysis by keeping continuity of constructional process and simulating interaction of different parts in integrated model precisely, and reach to a design-required structural state accurately after finishing constructional process.