As a natural extension of work [4], in this paper the calculation of zero field splitting parameter D of 3d5 ions in low symmetry ( C4v or D4h,C3v or D3h ) crystal field is discussed. The expressions of parameter D in terms of Racah parameters, crystal field parameters and spin-orbit coupling constant ξ are obtained. Applying to Fe3+ in α -Al2O3 crystal, the calculated result agrees fairly well with the experimental value.