Urban rail engineering faces significant challenges with regard to an earthquake resistant design of underground structures. The response displacement method is a simple method, which is widely used to design such structures. Thus, determining the ground spring constant in the seismic design of underground structures is very important. Four typical determination methods are introduced:the test method, Li's method, the MIDAS method, and the finite element method. Based on the values of the ground spring constant determined through these four methods and considering the local geological conditions in Beijing, response displacement models are used to obtain the bending moment, axial force, and shear force of the underground structures. The four determination methods are compared on the basis of their respective advantages and disadvantages. The results show that the values of the ground spring constant have a significant influence on the internal force response of underground structures. Moreover, using the response displacement method, we observe that the constant has a greater influence on the axial force and shear force and comparatively lesser influence on the bending moment. The test method is recommended for designers, when geological survey data are not available. The empirical formula and the finite element method can be used as alternative methods. In order to ensure design safety, the internal force of underground structures can be modified by a correction factor of 1.10, considering that the four typical determination methods have an impact on the internal force.