Abstract: Accelerator mass spectrometry(AMS) is the most sensitive analytical technique for measuring long-lived radionuclides, which is widely used in the fields of environment, geology, archaeology and physics. In recent years, the miniaturization of AMS device has been greatly developed in the world. In order to develop miniaturized AMS devices and their analysis technology, China institute of atomic energy has independently developed a single-stage AMS device with an acceleration voltage of 0.2 MV and a tandem AMS device with an terminal voltage of 0.3 MV, respectively. Based on the single-stage AMS device, the high efficiency transport technique and background eliminating method have been developed for ¹⁴C measurement, and realized the high sensitivity measurement of ¹⁴C. The measurement sensitivity reaches ¹⁴C/¹²C (atomic number ratio)=2×10^–15. Using the 0.3 MV tandem AMS device, the gas stripping conditions, background eliminating and detection methods of ¹²⁹I at low ion energy were systematically studied, and the high efficient transmission and high sensitive measurement methods of ¹²⁹I were established, the sensitivity is ¹²⁹I/¹²⁷I=1×10^–14. This is the first time to develop miniaturized AMS devices in China, which lays the foundation for the localization of AMS.