BIM is the grasp of digital transformation,but the BIM application is still in the modeling and management of the comprehensive,BIM as a collection of design data,the application of BIM in the design process of the data generated by BIM is also a new direction of research in the industry,the data simulation of system flow-head can only be carried out separately through the new simulation model in the past,this article can find a convenient way to obtain the system resistance in the BIM environment,and provide reference for the further application of BIM data in the HVAC industry.