Abstract: Focusing on the problem of large settlement of a test building, the main reasons for the foundation settlement and differential settlement are obtained through investigation of crack distribution and analysis of the observed settlement variation. The surface water seepage, the obvious rising groundwater level and the foundation settlement of adjacent buildings are the main reasons. In order to solve the problem of differential settlement of foundation caused by uneven collapsible deformation, a pit-type static pressure underpinned pile scheme was proposed to carry out the foundation reinforcement treatment, and the reinforcement design scheme and construction technology were introduced in detail. By comparing the settlement observation results before and after reinforcement, it shows that the pit-type static pressure underpinned pile has better reinforcement effect, which can effectively restrain the uneven foundation settlement of the collapsible loess site, and accumulate regional experience for similar reinforcement projects.