This paper introduces two basic concepts of digital engineering which are digital twins and digital threads，their relationship and their application in the construction of American military equipment projects. The concept of digital baseline is defined on the basis of the traditional technical state baseline in order to clearly interpret the important role of the two technologies in the construction of modern military equipment. The application requirements of digital twin and digital link technologies in the whole life cycle of our military weapons and equipment are explored. Finally，problems existing in the development of digital engineering technology in equipment projects are analyzed，and the corresponding suggestions are put forward.
