Abstract: The developing law of T800/epoxy prepreg property parameters during curing process was analyzed through tests. A finite element analysis (FEA) simulation method of staged cure-induced deformation based on stress transfer was proposed in view of phased molding of composite integrated structures under the autoclave conditions. For I-shaped stiffened structures fabricated in different processes, deformation results predicted by the phased simulation were compared to experimental results and relationships between different manufacture schemes and deformations were also analyzed. The results show that the simulation method proposed in this paper can accurately predict the cure-induced deformations for the integrated structures, deformation is closely correlated with fabrication process, and selecting appropriate fabrication process for special structure and lay-up can effectively reduce the cured-induced deformations of composite structures.