Drift-PBA method has been widely used in the construction of metro station. Yet the discussion about the excavation sequence of headings was still a controversy. In this paper, three-dimensional numerical simulation of a metro station construction by drift-PBA was conducted by MIDAS/GTS. The heading construction sequence was studied in the environmental impacts due to the construction, and some suggestions were provided for the site. The calculation results indicated that excavating the upper headings previously could effectively control the shapes of settlement troughs and the deformations of pipelines, and diminish the disturbance to the stratum.