For underground structures with large spans, such as buried pipelines, the seismic motions may vary not only at distinct horizontal locations due to the wave passage, incoherence and local site effects; but also at different vertical soil depths owing to the site amplification effect. This paper numerically investigates the influences of underground spatially correlated earthquake motions (USCEMs) on the seismic behaviors of large-span buried pipelines. To accomplish this task, the widely used buried gas steel pipeline of API X65 is chosen as a case study and the corresponding three-dimensional finite element (3D FE) model is created using the ABAQUS software, which accounts for the soil-pipe interaction (SPI) by the beam on nonlinear Winkler foundation (BNWF) model. The three-dimensional USCEMs for the nonlinear time-history analyses of the buried pipeline are stochastically synthesized based on the computed underground transfer functions of local sites. A total of 11 analysis cases associated with different spatial variability parameters of USCEMs (i.e. seismic excitation type, incoherence loss, local site condition and seismic motions at different soil depths) are considered. Based on increment dynamic analysis (IDA), a parametric study is carried out to comprehensively examine and discuss the influences of different spatial variability parameters on the seismic responses and critical operable capacity of the exemplar buried pipeline by comparing the analysis results of different cases. Numerical results demonstrate that these influencing factors can impact the seismic behaviors of the exemplar buried pipeline in different degrees and cannot be neglected in the seismic analysis. This research can serve as a vital reference for the seismic performance assessment and design of large-span buried pipelines.