Today, reactive dyes for dyeing cellulosic fiber are the most important reactive dyes. The paper addresses the development of such reactive dyes in six technology aspects: the technology for improving fixation rate, the technology for improving dye-uptake, the technology for improving fastness; the technology for improving levelness and reproducibility; the technology for developing dyes for low-salt dyeing process and the technology for improving blackness of reactive black dyes. It also introduces the latest development in dyeing cellulosic fiber with reactive dyes.