[Purposes] The influence of various influencing factors of basement soil reinforcement on the deformation of ultra-long deep foundation pit was comprehensively considered, and the design of the reinforcement scheme was optimized. [Methods] Based on the foundation pit project of a subway station, FLAC3D finite element software was used to numerically simulate the excavation of the foundation pit, and the orthogonal test method was used to comprehensively analyze the influence of the planar design shape and reinforcement parameters of the basement soil reinforcement on the lateral displacement of the underground continuous wall and the vertical displacement of the foundation pit. In addition, the influence of various factors on the above displacement indexes was analyzed and determined. [Findings] The different plane design shapes of the basement soil reinforcement have different effects on the deformation of the ultra-long deep foundation pit, and the reinforcement method of the entire basement soil has a significant control effect on the deformation of the foundation pit. The reinforcement method along the diaphragm wall can also play a good role in controlling the deformation of the diaphragm wall. Different reinforcement parameters have different effects on foundation pit deformation, and the deformation control effect gets better with the increase in cement content and reinforcement thickness. The plane design shape of the basement soil reinforcement has a great influence on the deformation control of the ultra-long deep foundation pit, and the reinforcement thickness and cement content have relatively little influence on the deformation control of the ultra-long deep foundation pit. The control effect on the deformation of the foundation pit is the most ideal when the reinforcement method of the entire basement soil is used with a cement content of 14%-16% and reinforcement thickness of 10-12 m. [Conclusions] In the design of an ultra-long deep foundation pit, the plane design shape of the basement soil reinforcement should be considered, and the influence of the reinforcement parameters on the foundation pit under the plane design shape should also be comprehensively considered. In the design of the same type of foundation pits, priority should be given to the plane design shape of the reinforcement method of the entire basement soil, and the cement content and reinforcement thickness can be appropriately reduced if necessary, so as to improve the economic rationality of foundation pit engineering design.