Abstract: When designing structures,engineers should pay attention to various structural changing that may arise in the construction process.Construction enterprises should do their work strictly according to relevant laws and regulations.In the construction process of a shopping mall,the provisional supports on both sides of post-cast strip were removed earlier than required in order to improve the utilization of molds,which caused floor sinking deflection up to about 9 cm.Finite element software ANSYS was used for simulation of the process in which the reinforcement across the post-cast strip was modeled as link element.The finite element model of structure without support between adjacent floors was made.After analysis and calculation,the damaged parts of the structure were located,and the maximum deflection of prediction was 11 cm or so,which was consistent with the actual structure.Furthermore,the capacities of the structure with the existing geometry were analyzed for afterwards strengthening after closing the post-cast strip.