Calculation result indicates that the lowest Kramer’s doublet of the low-spin d5 complexes proposed by Prof. W. C. Lin and the first order approximate matrix derived by us from the 1.s matrix table of d1 ion and the hole energy level model put forward by Prof. W. C. Lin and Taylor respectively are more suitable to the calculation of EPR parameters of the low-spin d5 complexes. The calculation conditio gzz>gyy>gxx>0 established by Taylor is used by us to obtain two parameters simultaneously, i.e, the orbital reduction factor k of a positive number near to unity, and the rhombi-city λ in range from 0 to 1/3 which is a satisfactory quantitative para meter. The same accurate EPR parameters can be obtained from both this method and Griffith’s method. Calculation result indicates that the lowest Kramer’s doublet of the low-spin d5 complexes proposed by Prof. WC Lin and the first order approximate matrix derived by us from the 1.s matrix table of d1 ion and the hole energy level model put forward by Prof . WC Lin and Taylor respectively are more suitable to the calculation of EPR parameters of the low-spin d5 complexes. The calculation conditio gzz> gyy> gxx> 0 established by Taylor is used by us to obtain two parameters simultaneously, ie, the orbital Reduction factor k of a positive number near to unity, and the rhombi-city λ in range from 0 to 1/3 which is a satisfactory quantitative para meter. The same accurate EPR parameters can be obtained from both this method and Griffith’s method.