China’s urban housing demand has directly influenced urbanization development. To stabilize the level of urbanization, it is urgent to optimize the whole life-cycle efficiency of construction and the preliminary design as the first step is even more significant. Building Information Modeling (BIM) is widely used as information technology in the construction industry to promote the implementation and management of projects. However, the traditional preliminary design approach still occupies the mainstream market without forming a systematic BIM workflow, which causes inefficiency. To address this issue, this research aims to construct a BIM-assisted workflow to enhance the preliminary design efficiency of architecture. This study creates traditional and BIM-assisted workflows for comparative analysis to capture duration data with a questionnaire and validate by practical simulation. The findings show that the BIM-assisted workflow consumes less time than the traditional workflow. This research indicates that the BIM-assisted workflow can significantly reduce operation time to enhance preliminary design efficiency and deserves to be strongly promoted in the Chinese Architecture, Engineering, and Construction (AEC) industry.