$eta$-Sialon powders were prepared by the reduction-nitridation reaction from the mixture of Wando-pyrophyllite and graphite at 135$0^{circ}C$ in $N_2-H_2$ atmosphere. The $eta$-Sialon powders were sintered at 175$0^{circ}C$ by the pressureless sintering for 90min and the hot-pressing for 60 min respectively. All the sintered bodies showed their relative densities higher than 94% The values of M.O.R fracture toughness(KIC) and hardness showed 32.9kpsi 2.9MN/$m^{1.5}$ , 12.1GN/$m^2$ for the pressure-less sitnered bodies and 48.6kpsi, 4.6 MN/4m^{1.5}$ 15.3GN/$m^2$ for the hot-pressed bodies respectively.