Under the condition of specific pulse discharge parameters, the discharge mode conversion of the low-temperature plasma jet discharge channel that originally propagated along a straight line will occur, forming a three-dimensional helical plasma channel. Different from the traditional helical wave discharge, there is no external constant magnetic field in the experiment to destroy the poloidal symmetry of the dielectric tube, and the chiral direction of the helical streamer will change with the discharge parameters. In order to deeply understand the electromagnetic mechanism of the helical structure in the plasma jet, and understand the source and influencing factors of the poloidal electric field that leads to the helical shape and determines the chirality in this new type of discharge, we analyze the complex characteristics and electromagnetic mechanism of the helical streamer, such as the chiral direction, pitch, branching, by establishing a self-consistent plasma theoretical model. It is found that the phase of the poloidal wave mode has an effect on the chiral selection of the helical streamer, the electron density has an effect on the pitch of the streamer, and the repetition frequency has an effect on the bifurcation point. The above discharge characteristics and their influencing factors have important scientific significance for exploring the interaction mechanism of electromagnetic wave and plasma, and also provide experimental and theoretical support for the chiral application of low-temperature plasma.