A railway station subgrade (RSS) is a complex earth structure for supporting various railway facilities and its building information modeling (BIM) is an essential task in a railway station project. During the entire life cycle of an RSS BIM model, it will be frequently updated according to the progress of the project. However, the current way of updating an RSS model is commonly conducted in a complete rebuild, which is very inefficient and time-consuming. To address this issue, we propose a novel approach for realizing a partial BIM update driven by model changes, through which a quick update for an existing RSS BIM model can be achieved. A partial updating strategy that is triggered by a model change is developed to locate a minimum influenced domain of the original model and update it in that domain. An actual railway station case is used for demonstrating the validity of the approach, through which a quick partial update to an existing RSS model is achieved by skipping the redundant computations in the process of a complete rebuild.