Lifting objects with extra weight and large span are more and more common in large-scale lift projects and it becomes more and more difficult for a single crane considering the limit of its lift capacity, which urges the wide use of dual-crane who can deal with the large-scale lift easily by the cooperation of two cranes. However, dual-cranes’ cooperation may be much more dangerous compared with single crane lift. To identify and avoid the potential danger during lifting, this paper focuses on 3D simulation of typical dual-crane cooperative lift and describes its model and basic motion expression. An effective simulating approach which follows the principle of space geometric constraints is put forward and an actual lift case validates the feasibility of the developed approach