Composites of SiC-Si3N4 consisted of uniformly distributed elongated $eta$-Si3N4 grains and equiaxed $eta$-SiC grains were fabricated with $eta$-SiC,. $alpha$-Si3N4 Al2O3 and Y2O3 powders. By hot-pressing and subsequent annelaing elongated $eta$-Si3N4 grains were grown via$alpha$longrightarrow$eta$ phase transformation and equiaxed $eta$-Si3N4 composites increased with increasing the Si3N4 content owing to the reduced defect size and enhanced crack deflection by elongated $eta$-Si3N4 grains and the grain boundary strengthening by nitrogen incorporation. Typical flexural strength and fracture toughness of SiC-40 wt% Si3N4 composites were 783 MPa and 4.2 MPa.m1/2 respectively.