The floating and cracking of a basement floor caused cracks in some of the retaining walls and masonry walls connected to it. Through the investigation of geological survey data, settlement monitoring, on-site entity detection and calculation analysis, the main reasons for the floating of the basement floor are summarized, and the corresponding reinforcement treatment methods are proposed for the foundation, concrete components and masonry wall. So far, the basement floor has not cracked and floated again, and practice has proved that the reinforcement method is effective. The results of this paper can provide a good solution and treatment ideas for similar projects.