In this study, monolithic liquid phase sintered SiC (LPS-SiC) was made by the hot pressing method with nano-SiC powder, whose particle size is 30 nm and less on the average. Alumina ($Al_{2}O_{3}$), yttria ($Y_{2}O_{3}$), and silica ($S_{i}O_{2}$) were used for sintering additives. To investigate the effects of $S_{i}O_{2}$, the $Al_{2}O_{3}/Y_{2}O_{3}$ composition was fixed and the ratio of $S_{i}O_{2}$ was changed, with seven different ratios tested. And to investigate the effects of the sintering temperature, the sintering temperature was changed, with $1760^{circ}C,;1780_{circ}C$, and $1800_{circ}C$ being used with a $S_{i}O_{2}$ ratio of 3 wt%. The materials were sintered for 1 hour at $1760^{circ}C,;1780^{circ}C$ and $1800^{circ}C$ under a pressure of 20 MPa. The effects on sintering from the sintering system used, as well as from the composition of the sintering additives, were investigated by density measurements. Mechanical properties, such as flexural strength, were investigated to ensure the optimum conditions for a matrix of SiCf/SiC composites. Sintered densityand the flexural strength of fabricated LPS-SiC increased with an increase in sintering temperature. Particularly, the relative density of a sintered body at $1800^{circ}C$ with a non-content of $S_{i}O_{2}$, a specimen of AYSO-1800, was 95%. Also, flexural strength was about 750MPa.