The purpose of this study was to optimize the solid state cultivation of Monascus ruber on sterile rice. A single-level-multiple-factor and a single-factor-multiple-level experimental design were employed to determine the optimal medium constituents and to optimize carbon and nitrogen source concentrations for lovastatin production. Simultaneous quantitative analyses of the ${eta}$-hydroxyacid form and ${eta}$-hydroxylactone for of lovastatin were performed by the high performance liquid chromatography (HPLC) method with a UV photodiode-array (PDA) detector. The total lovastatin yield ($4{sim}6;mg/g$, average of five repeats) was achieved by adding soybean powder, glycerol, sodium nitrate, and acetic acid at optimized levels after 14 days of fermentation. The maximal yield of lovastatin under the optimal composition of the medium increased by almost 2 times the yield observed prior to optimization. The experimental results also indicated that the ${eta}$-hydroxylactone form of lovastatin (LFL) and the ${eta}$-hydroxyacid form of lovastatin (AFL) simultaneously existed in solid state cultures of Monascus ruber. while the latter was the dominant form in the middle-late stage of continued fermentation. These results indicate that optimized culture conditions can be used for industrial production of lovastatin to obtain high yields.