Al

2

O

3

-TiC/Al composites were prepared by adding CO

2

into Al-Si alloy melt containing Ti.Microstructure of the composites has been observed by X-ray diffraction（XRD）

scanning electron microscope（SEM）and transmission electric microscope（TEM）.It is found that Al

2

O

3

and TiC particle with grain size of 0.2～1.0 μm formed from in-situ reaction of CO

2

with Al and Ti can be uniformly distributed into the matrix.In addition

formed Al

2

O

3

and TiC numbers are obviously dependent on the injection time of CO

2

.