β cyclodextrin grafted maleic anhydride(MAH β CD) was synthesized by esterification of maleic anhydride(MAH) and β cyclodextrin(β CD). The effect of n(MAH)︰n(β CD), reaction time and reaction temperature on the yield of MAH β CD was investigated. The results show that the yield of MAH β CD is 75%(by mass) when the n(MAH)︰n(β CD) is 10︰1 and reaction is carried out at 90 ℃ for 8 h. A new set retarding type polycarboxylate superplasticizer(RPC) was prepared by free radical solution copolymerization of acrylic acid(AA), allyl polyethylene glycol(APEG), sodium methylacrylsulfonate(MAS) and MAH β CD. Based on the test result of fluidity of cement paste, the synthesis process of RPC is carried out at the n(AA)︰n(APEG)︰n(MAS)︰n(MAH β CD)=5.000︰1.000︰0.500︰0.075 in the presence of 5%(mass fraction of monomers) APS at 80 ℃ for 5 h. The chemical structure of MAH β CD and RPC was characterized by FTIR and 1H NMR. The application result in concrete for RPC indicates that the set retarding time is 5 h longer and water reducing rate is as higher as 32%(by mass). The concrete with RPC does not show any segregation and bleeding, the early compressive strength is improved significantly.