In order to meet the requirements of batch and high-efficiency development of aerospace products, an automatic measurement method based on product mathematical model is proposed. On the basis of mathematical analysis of product mathematical model, a calibrated object is preset on the assembly module and its position information is calibrated. The calibrated object is taken as the measurement object in the assembly process and the instrument is used to self-calibrate. Dynamic sampling and automatic evaluation to achieve rapid measurement and determination of assembly status of components. Experiments show that this method has high automation, wide application and strong adaptability. It can reduce the error rate of field data and significantly improve the measurement efficiency.