Abstract: In order to investigate the problem of mode transition of radio frequency Ar inductively coupled plasma under the influence of axial magnetic field, a small inductively coupled plasma generator experimental system was designed and built. The impedance analysis method was used in the experiment, also verified correct by Langmuir probe method. It is found out that, when the pressure is 10 Pa, the increase of axial magnetic field intensity will increase the discharge power of E-H and H-E mode transitions. At the same time, the stronger the magnetic field is, the lower the electron density at the center of discharge area is. According to some preliminary analysis, charged particles make cyclotron motion at the influence of Lorentz force, which leads to the reduced collisions of high-energy electrons in the direction perpendicular to the magnetic field. Accordingly, electron density decreases and power coupling efficiency decreases. Further analysis on electron energy probability function (EEPF) has suggested that axial magnetic field has stronger restriction on electronic motion under E mode than H mode. As a result, the reduced collisions lead to a higher high-energy (>27 eV) proportion and a more uniform electron energy probability function under E mode, which has conformed with aforementioned analysis.