With the speedy development of Beijing mass transit, the land for metro engineering construction is becoming more and more insufficient; moreover, more and more complicated building environment problems are coming forth in future. In a complex building environment, how to choose available construction method to fast, safely and economically build metro engineering is worthy to be urgently studied in Beijing mass transit. Taking the experiment project of Beijing metro line No.14 as an engineering background, a new construction method that a running tunnel is firstly built by large-size shield method and then a metro station is constructed by shallow mining method to enlarge existing large-diameter shield tunnel is presented in this paper. Based on the building conditions of the experiment project, three architectural design schemes for the metro station and two kinds of construction plans are briefly introduced, and their advantages and disadvantages are analyzed as well. The new construction method can be used as a reference for the design and construction of metro engineering in China in the future.