Abstract: This article uses BIM technology to establish a model of foundation pit support and pre replacement of internal support for post pouring strip. The construction process of pre replacement of internal support and the installation position of I-beams are simulated through animation. After review by the design unit, the model is implemented to achieve pre replacement of support and early removal of internal support using cutting method. A post pouring strip detachable and adjustable quick support device composed of support plate, steel plate group, and section steel is designed and optimized, Simplifying the traditional installation and removal process of independent steel pipe supports, adopting the cutting method to remove internal supports in advance, achieving early replacement of supports, accelerating construction progress, saving resources and costs. The research on this technology is a new direction of BIM technology in construction project safety management.