Polyester microfiber has usually greater dye uptake than normal denier polyester fiber at the same dyeing condition. Though polyester has high dye uptake, dyed microfiber fabric has not only low visual colour depth but also poor washing fastness property. In order to improve this dyeing property, poly(ethylene terephthalate/trimethylene terephthalate)(ET/TT) was synthesized with various TT content using DMT process. The feed ratio of TT was varied from 5-30 mol%. The content of TT unit in P(ET/TT) was higher than the feed ratio of TT. The physical properties, dyeing properties, and wet fastness of P(ET/TT) were investigated. Melting $point(T_m)$ and glass transition $temperature(T_g)$ of P(ET/TT) decreased with increasing content of TT unit. P(ET/TT) could be dyed at lower temperature than homo PET with increasing TT feeding content. Alkaline dissolution behavior of P(ET/TT) was also examined as a function of TT content.