Abstract: To protect an in service limestone crusher at the quarry side from damage due to impact of the flying rocks,a protecting structure needs to be designed and constructed.Concrete-filled square steel tube columns and steel braces were used as the vertical structure system for the protecting structure.A two-way steel-concrete composite slab-on-girder system was used as the roof structure.After performing comparison analyses,a layer composed of(soil-steel plate-soil) was used to absorb the impact energy of the flying rocks and to act as a buffer layer and a protecting layer on the roof top.Simulation analyses of responses for the roof impacted by the flying rocks were performed using the general software ANSYS/LS-DYNA and the analysis of the whole structure was performed using the software SAP 2000.The results show that the proposed structure achieves the requirement of resisting the impact of the flying rocks with the maximum volume of 1 m~3 and the maximum falling height of 160 m.The proposed protecting structure in this paper can be a reference for common industrial buildings and civil buildings to resist the falling objects from high altitude.