As an indispensable work in the construction process, the foundation pit deformation monitoring plays a very important role in improving the quality and safety of the whole building. Therefore, after the completion of foundation pit construction, a combined foundation pit deformation monitoring method of the traditional one and the 3D laser scanning technology is conducted for monitoring the foundation pit deformation, making the monitoring more intuitive, which promotes the overall quality of the foundation pit. This paper mainly introduces the basic principles of 3D laser scanner, as well as its advantages over traditional surveying and mapping methods. Taking the foundation pit of the new student service center in dalian university project as an example, this paper also describes the method and process of using 3D laser scanning technology to model the foundation pit surveying and mapping, and also summarizes and prospects the application of 3D laser scanning technology in the foundation pit construction.