Based on the theory of (life Cycle Assessment,LCA) and the mid-point model, the method of centre of environmental science (CML) is chose to evaluate the environmental impacts of construction in urban rail transit by considering global warming (GWP), acidification (AP), eutrophication (EP), non-living resources consumption (ADP), human toxicity (HTP), photochemical smog (POCP) as the evaluation index. Therefore, a new model for assessing the environmental influences of construction in urban transit station by introducing the construction characteristics of urban rail transit station which is built by undercutting method. Finally, an urban rail transit station in Beijing is evaluated by the model and the results show the proportion of the environmental impacts of secondary structure in the major structure is more than 50% in the total impacts. The environmental impacts of the evaluation index from large to small are as follows:GWP,AP,POCP,EP,ADP and HTP, which provide support for energy saving and emission reduction in the construction period of urban rail transit station.