The invention discloses a set-retarding type efficient dispersant. The set-retarding type efficient dispersant is characterized in that a melamine derivative serves as a core, -PO3H2 and polyoxyalkylene side chains serve as the periphery and are independent from each other, but the periphery cannot be -PO3H2 or the polyoxyalkylene side chains completely simultaneously; the weight-average molecular weight of every polyoxyalkylene side chain ranges from 1,000 to 3,000, one terminal of every polyoxyalkylene side chain is exposed-OH while the other terminal thereof is unexposed fatty group or aromatic group, and every polyoxyalkylene side chain is prepared by direct oxyalkylation of corresponding fatty alcohol or aromatic alcohol. The set-retarding type efficient dispersant has a certain water reducing and slump retaining performance and remarkable set-retarding effect, and is highly adaptable to current low-grade concrete raw materials, strong in market demand, advanced in preparation technology and low in cost, thereby being promising in prospect and hopefully being developed into core technology of the concrete water reducing agent field to lead industry development.