The characteristic luminescence near 5000cm

-1

in vanadium-activated Ⅱ-Ⅵ compounds is ascribed to the transition

4

T

2

(drde

2

)→

4

T

1

(dr

2

dε)within the V

2+

ion which is in a crystal field of T

d

symmetry. According to the complete dia-gonalization calculation of energy matrix

the appropriate crystal-field parameters are derived as follows:B=0.4B

0

C=5.0Band D

q

=1.7B. This avoids the difficulty of "T

d

forbidden"which occurs in other models

and qualitatively exp-lains the main charaters of positions

intensities and shapes of excitation spectra of ZnS:V

CdS:V

CdSe:V and CdS:V(Cu)

Furthermore

the first step correction fo-mulas of energy are derived by using the irreducible tensor method of Y.Tanabe and H.Kaminura when the symmetry is lowered from T

d

to C

3

t and the spin-orbit coupling is considered. As an example

the first step correction of CdS:V (Cu)is carried out and it is shown that the broad split of the first excitation band(8820cm

-1

~9500cm

-1

)can also be explained in this model.