Abstract: In order to eliminate the common faults of Isoprime 100 stable isotope ratios mass spectrometer in the determination of δ¹³C and δ¹⁵N, the causes of the failure of leak detection, unqualified peak center detection and unsatisfactory stability of the system have been analyzed. Combined with the actual operation, the preventive measures of instrument faults were summarized from the aspects of pre-test state inspection, test process monitoring, maintenance of all components after test, etc. At the same time, troubleshooting methods were proposed for system leakage, ion source damage, mechanical pump damage, etc. By taking the above measures, the accuracy of test data is ensured, the failure rate of the instrument is reduced, the service life of the instrument is prolonged, and the timely and efficient application of the instrument in teaching and scientific research work is guaranteed.