Abstract: Quadrupole mass filter is a matured miniature mass spectrometer that has been widely used.Ions in the quadrupole field experienced strong focusing are concentrated to the center of the quadrupole mass filter.The motion of the ions can be expressed by Mathieu Equation and its stability diagram.The mass spectrum of the analyzed ions can be achieved by scanning the amplitude of the RF voltage.Quadrupole mass filter is a matured commercial instrument which has a long history of more than 50 years and the studies on it are still ongoing.The main studies focus on miniaturization,wider applications,higher resolution and wider mass range,rapid analyzing and lower cost.