Abstract: This paper deals with the information of using a microcomputer forreal-time sampling and data processing in stable isotope ~(15)N mass spec-trometry. The good results were obtained with both mass spectrometers,ZHT-1301 (single inlet and single collector) and ZHT-03 (double inlet anddouble collector). In addition, the re-adjustment of single beam massspectrometer's technical specifications are described.