Microwave frequency standards have been widely used and played an indispensable role in many fields such as satellite navigation, precision measurement, electric power and communication. In recent years, many scientific research institutes in the world have been carrying out research on new?type microwave frequency standards. Among them, the microwave frequency standards based on trapped ions have the advantages of high performance and miniaturization, and have become a new generation of microwave frequency standards of great concern. This paper reviews the research status of ion trap microwave frequency standards, introducing the working principle of Penning trap and Paul trap, and the research motivation, application fields, physical solutions and technical specifications of various ion trap microwave frequency standards, including frequency standards based on ¹⁹⁹Hg⁺, ¹¹³Cd+, ¹⁷¹Yb⁺ and so on. Finally, the application prospects of ion trap microwave clocks in timekeeping, deep space exploration and other fields are introduced.