Based on the distribution function got by solving the dynamic equation,the flux distribution and its features of ionospheric heavy ion O+
originating in the auroral zone on the meridian plane are studied.The results show that:1.the flux distribution of the O+
along the z-direction mainly appears as a peak--like structure,its maximum reduces as the geo-centre distance increasing and more quickly in near geo-space than that in far geo-space;2.the ion O+
exists in larger geo-space and the flux peak is less prominent when Kp
=3-5 than that when Kp
=0;3.the calculated flux of the ion O+
in the boundary of the plasmasheet is about 105cm2.s-1.The results are consistent with the observation.