The J-O theory used to calculate optical properties of Er

3+

in oxide-fluoride glass

the oscillator strengths

transition probabilities

branching ratios and the lifetimes were obtained.The absorption spectra

emission spectra

and excitation spectra were measured. We present a preparation method of fluoride-oxide glass (MFT) containing TeO

2

PbF

2

AlF

3

BaF

2

NaF

doped with Er

3+

ions.The impurity concentration of Er

3+

in this sample is 2mol%.Based on the J-O theory the optical transition properties were calculated using the absorption spectra data.The J-O parameter Ω

2

Ω

4

Ω

6

are 1.637E-20

0.225E-0

0.480E-20

respectively.The oscillator strength

transition probabilities

the branching ratios and radioactive transition lifetimes were obtained.The calculated results are analogous with experimental observation.The excitation spectra were measured at 550 and 660nm.The emission spectra were measured under different excitation wavelength related to the excitation spectra.