Abstract: Aim at an adding story workshop collapsed,firstly,the accident-location investigation is carried out and structural bearing capacity is calibrated by using SAP 2000 finite element software.Then,the reason why the adding story workshop collapsed was analyzed and a verdict was got from the two aspects of design and construction.Finally,conclusions and recommendations were presented,meanwhile,the treatment method was proposed.Studies have shown that there are many illegal operations in design and construction of the project,all kinds of defects accumulated and interwoven led to the accident.Therefore,in construction,only a sound regulatory system of construction has been established,and the projects have been designed and constructed strictly in accordance with the relevant norms and standards,the level of project quality will be improved and the occurrence of work accidents will be avoided.