Abstract: Gas detectors are widely used in the early development of nuclear physics. Due to the development of semiconductor detectors, they have gradually been replaced by semiconductor detectors. However, they have many advantages in heavy ion physics experiments, such as simple preparation, reliable performance, low cost, easy to use and so on. However, with the development of miniaturization and low energy of accelerator mass spectrometers, particle detection technology has encountered difficulties. Accurate determination of heavy ions at low energies is an important scientific issue. The thin window gas ionization chamber is a new type of gas detector developed for low energy accelerator mass spectrometry in recent years. The silicon nitride film used as the entrance window of the detector enable a higher resolution for its thin and uniform characteristics, and has been initially applied in low-energy particle detection technology, and has a wide range of application prospects. In this paper, the basic principle, the comparison of thin silicon nitride films with those of Mylar films, low-energy particle pulse height comparisons of different Z (proton number), thin-window gas detectors and silicon detectors and application of thin window gas detectors were reported.