The Y

2

O

3

:Eu

3+

nanocrystals scatered in SiO

2

hosts were synthesized by sol-gel method. According to XRD patterns

the samples calcined at 800℃ were noncrystals and the size was smaller. The calcining temperature was elevated to 1000℃

the crystalline phase began to occur and the nanocrystals were well crystallized at 1200℃ and the particle size did not become large. The spectrum principles of Y

2

O

3

:Eu

3+

nanocrystals scattered in SiO

2

for different annealed temperature and concentration have been intensively discussed. At ultraviolet laser excitation at room temperature

the emission intensity of samples increased with elevated annealing temperature for the same concentration. For the same annealing temperature

the intensity became strong as the increase of concentration. The intensity of

5

D

0

7

F

0

was stronger than of

5

D

0

7

F

2

and the origin was analysed. Appropriate doped concentration and calcining temperature were studied. The excitation spectra and site-selective excitation spectra for 5% Y

2

O

3

:Eu content (mass fraction) calcined at 1300℃ were measured. The average size was 50 nm. According to selective excitation spectra of

5

D

0

7

F

1

and

5

D

0

7

F

2

Eu

3+

occupied four sites.