Abstract: In compact accelerator mass spectrometry (AMS) systems, the detection of low-energy ions is often interfered by interfering ions with the same magnetic rigidity and electric rigidity as the target nuclide. To address this issue, a gas detector with range detection capability was developed for low-energy small-scale AMS. By exploiting the different ranges of the target nuclide and interfering ions, all interfering ions are absorbed in an absorber chamber while the target nuclide can pass through and enter an amplification chamber with proportional amplification functionality, thus facilitating the measurement of the target nuclide. To validate the performance of the gas detector, a series of calibration experiments were conducted using 5.8 MeV alpha particles. Experimental and simulation results demonstrate that the absorber chamber effectively absorbs interfering ions of different energies, and the energy resolution of amplification chamber is around 30% for the one-way signal. At the same time, when the reduced field strength in the amplification chamber is at 5 V·mm⁻¹·hPa⁻¹, the signal can be amplified by about 7 times. The energy resolution of the combined signals from the absorber and the amplification chamber is improved to around 20%, laying the foundation for the measurement of nuclides such as ²⁶Al in low-energy small-scale AMS.