The invention provides a polyether-based polycarboxylic acid series hyper-dispersant which is prepared by copolymerization of polyethlene glycol and unsaturated carboxylic acid or the ramification under the action of redox system catalyst, and a synthesizing method which belongs to the water reducing agent field. The method uses the new type redox catalyst, synthesizes a polyether-based hyper-dispersant with high efficiency. The method has simple processing technique, conquers difficult operation caused by low reaction temperature and energy waste caused by high temperature. The hyper-dispersant and the synthesizing method have advantages of environmental-friendly, low energy consumption and low cost.