Abstract: A microcomputer-based system for control and data processing of a ZLS-150 quadrupole mass spectrometer is developed and described in detail in this paper. Least-sqare technique is adoped for handling the mass calibration. On the basis of the intensive studies and analysis of the mass scanning phenomena, a new concept of fixed point scanning technique is put forward. Thus, the problem of handling the number of components monitored and the scanning frequency is solved quite well. Experimental studies show that this technique is practical and satisfactory.