The preparation and toughening of SiC-AIN solid solution from powder mixtures of $eta$-SiC, AIN and $alpha$-SiC by hot-pressing were studied in the 1870 to $2030^{circ}C$ temperature range. The reaction of AIN and $eta$-SiC(3C) powders causing transformation to the 2H(wurtzite) structure appeared to depend on hot-pressing temperatures and an additive of $alpha$-SiC. For the composition of 49wt% SiC with 2 wt% $alpha$-SiC and 47.5 wt% AIN47.5wt% SiC with 5 wt % $alpha$-SiC at 203$0^{circ}C$ for 1 h, th complete solid solutions with a single phase of 2H could be obtained. The appreciable amount of $alpha$-SiC could develop the columnar inter-grains of 4H phase and the stable 2H phase with the relatively uniform composition and grain size distributions. The effect of $alpha$-SiC on the phases present and compositional microstructures with columnar inter-grains was invetigated using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The fracture toughness and Vickers hardness of the hot-pressed solid solutions wre examined by the indentation-fracture-test method.