Abstract: Excavation of deep foundation pit has significant effect on adjacent buildings, threatening the safety of structures. Based on the case of a deep foundation pit excavation of certain metro station adjacent to an existing building in Kunming, the reinforcement scheme is optimized by numerical simulation, and the influence of reinforcement depth and position on the horizontal and vertical displacements of existing buildings is studied. The results show that the numerical simulation results are close to the measured data and numerical simulation can reflect the influence of deep excavation on the surrounding buildings; with the increase of reinforcement depth, the displacement of existing building gradually decreases and amount of displacement reduction decreases gradually once the reinforcement depth exceeds certain limit; with an increase of the distance of reinforcement position away from existing building, the displacement of existing building gradually increases, and gets small when the reinforcement position is closer to the foundation pit.