Abstract: The linear quadrupole rodset has become a very important scientific instrument which can be used to produce quadrupolar electric field distribution. Because of the special property of ion motion in the linear quadrupole system, it has been widely used to build quadrupole mass filter, linear ion trap, quadrupole ion guide and many linear quadrupole related tandem mass spectrometer. All of these equipments have become an essential chemical and biological analytical technique with numerous applications in many fields, such as bioscience, chemistry, geology, environment, food safety and so on. In this paper, the theory of the linear quadrupole was briefly reviewed, including the kinetics of ion motion in quadrupole field, the effect of rodset structure on the field distribution, the effects of higher order electric field on the property of mass analysis and ion transmission. Then the latest research results in the field of quadrupole mass analyzer and quadrupole ion trap mass spectrometry were introduced. On the basis of this, the research direction of the quadrupole electrode system is prospected.