The effect of process parameters on the optical property of the chromium/chromium compound multilayered thin film black matrix for liquid crystal display color filter has been investigated. A chromium compound layer was deposited reactively by DC magnetron sputtering, using gas mixture of Ar, CO2, and N2 on soda-lime glass substrate. Metallic chromium layer deposition was followed to enhance the light obstruction of the black matrix. X-Ray diffraction and transmission electron microscopy study showed that CrN is the major phase with unidentifiable oxides and carbides present as minor phases, in chromium compound layer, with nanocrystalline structure. Metallic chromium layer showed columnar growth structure. The ratio of CO2 in the reactive sputtering gas greatly affected the optical property of the multilayer, despite that N2 is the gas which contributes to the formation of the major phase. Delicate change of optical property is due to compositional variation of the compound layer, caused by reaction due to environmental changes. When processed with 10.28% of CO2 and 4.88% of N2 in 3.3 mTorr pressure, film with optical reflectivity of 3.31% at 655 nm of photon wavelength was obtained.