The trivalent rare earth ions have partially filled 4f

N

shell.In the free atomic states

4f

N

electrons contributes to same parity.In the bounded state

static crystal field leads to the mixing of opposite parity configuration

accordingly electronic dipole transition between 4f

N

configuration is allowed.Judd-Ofelt obtained the relationship between crystal field and the transition intensity based on the configuration mixing theory

and built up a method for calculating the transition intensity parameters from the absorption spectra.But the use of J-O theory is limited

because in a lot of conditions the measurement of absorption spectra is difficult. In this work

the absorption

excitation and emission spectra of Eu

3+

doped glasses

which contained PbF

2

and H

3

BO

3

was measured.The refractive index of different glasses was calculated.The Ω

2

and Ω

4

parameters of Eu

3+

for optical transition were calculated

in terms of reduced matrix U

(t)

(λ=2

4

6) character for optical transitions.The dependence of the Ω

2

and the Ω

4

parameter on the content of H

3

BO

3

was obtained and discussed.The purpose of this work is that

using the Eu

3+

as a probe to study the microenvironment in glasses.Lastly we attest to the possibility of this purpose in experiment.