A calculation of magnetic single-ion anisotropy in hematite (α-Fe2O3) has been made, based on point-charge model in crystalline field. The nearest-neighbor O2- ions and the nexi-nearest-neighbor Fe3+ ions were chosen as ligands and the effect of electrostatic shield provided by the O2- ions was taken into account. Considering the sixth order perturbation, we ob-tained an equivalent single-ion anisotropy field Hsi=102.3×102 Oe. Making use of this results in conjunction with the computed equivalent dipolar anisotropy field by Artmen et al,. the Morin transition temperature in hematite TM=261 K was obtained, which is in good agreement with the experimental value. Based on the linear approximation principle, we got the TM-n relation for low n value in α-(Fe-1nAln)2O3. With this relation the dependence of the-Morin transition temperature, TM, on n in low n value range could be explained quite well.