The boron carbide ceramics were prepared with carbon carbide as matrix and Al2O3

La

2

O

3

Y

2

O

3

and active carbon as sintering agent by vacuum heat pressure sintering. Effects of the rare-earth oxide on microstructure and mechanical properties of the ceramics were investigated. The results reveal that boron carbide ceramics with compact grain structure and desirable properties can be prepared with adding rare-earth oxide and sintering at 1850℃. The prepared samples with rare-earth oxide-free exhibit low properties as a result of a little generation of new phase Al8B4C7 and inadequate sintering

while the samples with La

2

O

3

exhibits a better properties and a desirable structure as a result of more fully sintering and amounts of generation of LaAlO3 phase

meanwhile

the properties of samples with Y

2

O

3

where trace residual Al2O3 and C exist are in range of above two due to low Y3Al5O12 generation.