In black dyeing of PET fabric, high concentrations of disperse dyes of three primary color are generally required, which leads low exhaustion level of dyes and discharge of unfixed dye into dyehouse effluent. In this study, the effect of combination ratio of dye concentration, liquor ratio, and dyeing pH on dyeing and color property of black dyed PET fabric was investigated. From the results, high K/S values and low lightness $(L^*)$ of PET fabric could be obtained with relatively small amount (1%owf) of yellow dye on condition that red and blue dye were used in high concentration. The dyeing results of red dye were consistent with those of yellow dye while blue dye did not follow the trend. Use of small amount of blue dye and large amount of yellow and red dyes resulted in PET fabric of grayish red color instead of black. Dyeing and color property of black dyed PET fabric were found to be dependent upon dyeing pH while not on liquor ratio.