The invention provides alkenyl carbonate polyethers. The general structure of the alkenyl carbonate polyethers is shown as follows, wherein R<1> is H or C1-C3 alkyl, R<2> is a C1-C5 alkylidene group, R<3> is a C2-C4 alkylidene group, a phenylene group or a benzylidene group, M is a polyether chain comprising one or more selected from -CH2CH2O-, -CH(CH3)CH2O- and -CH2(CH3)CHO-. The alkenyl carbonate polyethers comprise a carbonate group, thus facilitating enhancement of molecular chain toughness, and enhancing steric hindrance of synthesized water reducer molecules; and the carbonate group increases the side chain density of synthesized water reducers, and therefore dispersing performance of the water reducers can be improved. The carbonate group in the polyethers is high in electronegativity so that the prepared water reducers have certain functions of resisting slime adsorption. The polyethers are nontoxic, harmless, easily degradable and environmental friendly.