The invention provides a synthesis method of an unsaturated polyoxyethylene ether derivative. According to the method, an alkenyl phenol compound is used as an initial raw material is subjected to halogen substituting reaction with halogen gas; the obtained halogen substituted alkenyl phenol compound A and ammonia gas are subjected to substituting reaction with to produce an amino-substituted alkenyl phenol compound B; finally, the amino-substituted alkenyl phenol compound B and EO (ethylene oxide) or PO (propylene oxide) complete a polymerization reaction to obtain a target product. The invention also provides the unsaturated polyoxyethylene ether derivative prepared by using the method. The unsaturated polyoxyethylene ether derivative can be used for preparing polycarboxylate superplasticizers, so that polycarboxylate superplasticizers have excellent early strength effects; good application prospects are realized.