In view of the multi-disciplinary collaborative design complexity of radar system and the difficulty in ensuring the consistency management of technical states，a forward top-down collaborative design idea based on the bill of materials （BOM） structure is proposed.The model requirements are decomposed based on the task orientation，and the design process is analyzed based on a model-based systems engineering （MBSE） radar virtual prototype.Moreover，an idea for constructing the framework of a radar system collaborative design application platform is put forward，so as to realize the task coordination，driving，and closed-loop design iteration between the overall system and subsystems and subsystems.Finally，a radar system is taken as an example to demonstrate the rationality of the forward design process and modeling method for radar digital prototypes.