Abstract: the US Department of Defense's Dictionary of military language and related terms is the military language standard for the US military to formulate military plans, issue military instructions, carry out military operations, especially to participate in joint military operations and coalition military operations, with the highest authority. This paper introduces the dictionary from seven aspects: the scope of words, the purpose, the scope of application, the standard of inclusion, the way of term change, the format of printing and the leader. The continuous improvement and updating of the dictionary reflects the latest development of the theory of joint operations of the U.S. military, and has an important reference role for the study of the U.S. military.