In-situ ZrB

2

ZrAl

3

and Al

2

O

3

particulate reinforced aluminum matrix composites were fabricated by the direct melt reaction method in the system Al-ZrOCl

2

-B

2

O

3

.Analysis of the microstructure by scanning electron microscope （SEM） showed that the particulate with fine size lower than 2 μm was uniformly dispersed into matrix

and the volume fraction of in-situ particulates were increased with the increase of initial reaction temperature and reaction time.The aggregation and growth of particulate were formed with the melt temperature more than 900 ℃.It can be proved that the kinetic mechanism of the reaction system Al-ZrOCl

2

-B

2

O

3

is reaction-dispersion-crack by the analysis of water-quenched samples.