In order to optimize the process for development of super deep black fiber, the silica-containing polyester fabric, SN2000, was investigated in terms of mass reduction process by sodium hydroxide, selection of high color strength dyes, and resin treatment. As the results, the mass reduction condition which used 15g/L of sodium hydroxide at $120^{circ}C$ was determined and Dianix Deep Black Plus was selected for the best deep coloration at around 5% owf. Contrary to the prevailed understanding that the additional use of chromatic dyes would enhance the deep coloration, four kinds of chromatic dyes such as yellow, red, blue, and green dyes did not make great effect on the deep coloration. To increase the effect, the commercial resin that has low refractive index was used additionally and the resin made it possible to lower the lightness of the fabrics down to 8.7 which was generally accepted for super highly deep black fabric.