Abstract: The expressions of the ionizations in ionospheric D-region by relativistic, nonrelativistic and low energy particles of galactic cosmic ray are deduced individually, according to the theory of energy loss of charged particles in the earth's atmosphere. The global distribution of electron production rate q(h) and the electron density N(h) in the low ionospheric D-region by galactic cosmic ray is presented in this paper. The results show that the electron production rate and the electron density in the D-region by galactic cosmic ray have obvious latitude dependance. q(h) and N(h) at polar regions are 3-4 order of magnitude higher than that at low latitudes. The changes of q(h) and N(h) are quite small at R_c≥10GV. The effect of solar activity modulation on q(h) and N(h) are obvious, but its effects are far less than the effects of R_c on q(h) and N(h). The effects of p(h) on q(h) and N(h) are less.