The transmission characteristics of relativistic electron beams in the ion-focusing channel is given in this paper utilizing the single-particle theory, and the effects of the system parameters such as the ion-electron density ratio, the beam voltage and the beam current density on the propagation and focusing of the beam are discussed. The relativistic electron beam can be strongly focused by the ion channel,and it exhibits wave-like transmission as it passes through the ion channel. The radius of the focal point will gradually rise and the amplitude of the beam wave will reduce as the beam transmits in the channel .The results show that efficient transmission of relativistic electron beams in the ion-focusing channel can be reached by choosing appropriate ion-electron density ratio, b