SiC matrix composites can be reinforced and toughened by the second phase of AlN particles. SiC-AlN composites are mixed by ball milling of the SiC and AlN powders, and then hot pressed under 40 MPa at 1950oC in Ar atmosphere. The object of this paper is to understand the effect of AlN contents on the properties of SiC-AlN particulate composites. AlN content is between 5 and 40wt%. For improving to mechanical properties of siC-AlN composites, the composition range of SiC-AlN composites are between 90SiC-10AlN and 80SiC-AlN20(wt%). Less or more than this ratio would result in a microstructure with much pores or AlN grain-growth, respectively, two phenomena would decrease in the mechanical properties of SiC-AlN composites.