A new red phosphor Eu

3+

doped La

2

Mo

2

O

9

have been prepared by high temperature solid state method at 850℃ and the structure and luminescent properties of this phosphor were investigated. The XRD patterns show that single cubic phase La

2

Mo

2

O

9

crystal is synthesized in this experiment. The luminescent properties were studied by the excitation and emission spectra. The excitation spectra are composed of a broad band and a series of narrow bands; the excitation spectra include many narrow bands

which attribute to the intrinsic transition from

7

F

J

(

J

=1~4) to

5

D

J

(

J

=0

1) of Eu

3+

. The results indicate that this phosphor can be excited by UV light of 395 nm and visible light of 470 nm

also emit red light at about 620 nm. The luminescent intensity of this phosphor is more than 1.5 times of that of Y

2

O

2

S:Eu

3+

thus it can be used as red phosphor in the system of UV-LED based and blue-LED based white LED. The effects of Eu

3+

molar concentration and flux on the luminescence properties were studied in this paper. The results show the intensity will reach the strongest when the molar concentration of Eu

3+

is 30%; the NH

4

Cl is the appropriate flux and its most suitable mass fraction is 3%.