To expedite the process of loading export containers onto vessels, it is common for port terminals to gather containers in advance and stack them in container yards according to their attributes, such as voyage, port of discharge, weight and size. As modern container vessels are getting larger, the limited storage space a container yard provides needs to accommodate more containers. Consequently, how to use storage space more efficiently has become an essential consideration of container yard management. In this article, a mathematical model with time-space network is developed to deal with the storage space allocation problem for export containers in a container yard. A real-world case extracted from one of the dedicated container terminals at Kaohsiung Port is studied utilizing this model.