Abstract: Construction technology of separate pit divides a large foundation pit into several small foundation pits. Using the method of "time——space effect", successively construction often can effectively control the deformation of the long side of pit and ensure the safety of pipelines and buildings around. Based on a typical case of excavation, the paper analyzed influence of the surrounding environment in the case of zoned excavation and overall construction by Plaxis3D dimensional finite element numerical simulation. Then the simulated results were compared with the measured monitoring data. It is shown that construction technology of separate pit can effectively reduce the deformation of the long side of pit.