When using Inductively Coupled Plasma (ICP) as a machining tool, its processing method based on the principle of chemical etching leads to no contact stress between the tool and the material, thereby generating no mechanical damage. In recent years, this issue has been widely concerned in the field of optical fabrication. However, there are many differences between low power ICP jet and conventional ICP jet, one of which is that the former does not easily form a rotation-symmetric removal function due to its obvious pinch effect. In this research, the electromagnetism principle of the plasma pinch effect was analyzed firstly, and the jet shape under the pinch effect was classified. Then, experimental study was carried out on the plasma jet shape under the pure Ar and mixed gas of CF4-Ar, and the influence law of the reaction gas on the jet propagation shape was analyzed. Finally, the rotational symmetry of the removal function of plasma jet processing was optimized, and the nozzle design criteria based on pinch effect were proposed.