In order to determine the effects of functional groups of reactive dyes on the dyeability to cotton fabric, bifunctional reactive dyes, which contain the dichlorotriazine/vinylsulfone(DYE-DV) functional groups and the monochlorotriazine/vinylsulfone(DYE-MV) functional groups, were synthesized. The maximum absorption wavelength of ($λ_{max}$DYE-DV and DYE-MV was 512nm and 518nm, and the reaction yields of each dye were 75% and 89%, respectively. The synthesized dyes were compared in terms of the dyeability. The exhaustion amount of DYE-DV was smaller than that of DYE-MV. This means that DYE-DV is more substantive to cotton fiber than DYE-MV. But the fixation amount of DYE-DV was larger than that of DYE-MV at high temperature as well as at low temperature. And the wash-off property of DYE-DV was also better than that of DYE-MV due to its low substantivity.