Abstract: To meet the high requirements for reliability, stability and detection performance of gas analyzers in complex application scenarios, this paper develops a gas analyzer for gas composition analysis with a fully domestic-designed quadrupole mass spectrometer with a large mass range (1~1000 amu) as the core. To improve the performance of the instrument, design work is carried out on key links such as the precise sampling method for wide pressure variation, radio frequency power supply optimization and mass spectrum scanning mode improvement. The accurate sampling of gas samples at atmospheric pressure is realized, the problem of test mass discrimination is solved, and the resolution capability of mixed gases is improved. The performance test results show that the instrument has a stability test result of 2.98% and a repeatability test result of 2.15%, both superior to 5%. Its detection limit for inert gases is better than 2 ppm, and it has good resolution and repeatability for multi-component mixed gases (including ppm-level and percentage-level components). This design effectively improves the reliability, stability and detection accuracy of the gas analyzer, and can provide technical support for complex gas analysis in fields such as environmental monitoring, industrial control and scientific research.