The quantity take-offs (QTO) of prefabrication items during preliminary structural design are imported to clients and structure engineers. Instant feedback on the change of prefabricated components QTO provides an efficient way for design optimization. However, the current working process is non-automatic, which needs manual updates on the QTO information. This research aims to develop a systematic workflow to automate prefabricated construction components QTO calculation. This research uses Building Information Modeling tools like Revit and Dynamo to realize automatic export, import, read and write object data, parameters and solve prefabrication components’ design- feedback iterations.