The invention discloses a high workability reduction type polycarboxylic acid water reducer and a preparation method thereof. The molecular weight of effective components of the polycarboxylic acid water reducer is 10,000-150,000, and the structural formula of the effective components is shown in the description. According to the high workability reduction type polycarboxylic acid water reducer, by using fluorine-contained unsaturated carboxylic acid to synthesize the polycarboxylic acid water reducer, some fluorine-carbon bonds are contained in the molecular structure of polycarboxylic acid,so that the synthesized final product has higher surface activity, the surface tension of a solution can be effectively lowered, and the shrinkage of concrete is reduced.