Abstract: Architectural CAD standard is the foundation and premise for the implementation of collaborative design. And the key point is the CAD layer standards. In this paper, a systematic study on the CAD layer standards was made. Through the comparison and analysis of CAD standards made by famous large domestic building design companies and those built in several popular design software, some problems existed in current domestic CAD layer standards were pointed out. Moreover the specific solutions were provided. Finally, the outlook on BIM-based building collaborative design was given.