Abstract: Physical mechanism of producing non-focused high-current relativistic e-lectron beams and the beam characters are reported in this paper.Some key technologies of producing these beams,such as the formation and motion of the cathode plasma,the effects of the self-magnetic field of the electron beam on beam pinch,the uniformity of beam current density,and the formation of anode plasma and its effects are discussed.So far.there has not been a strict theoretical model which can be used to explain the electron beam behavior inside the diode in the world yet.A description of the studies which has been done in the world in this field and some improvements on the analysis of these problems,for example the effect of beam self-magnetic field on pinch and uniformity of current density distribution,are presented.