The invention relates to a soil insensitive polycarboxylic acid water reducer and a preparation method of the reducer. The water reducer is prepared by taking a 4-hydroxybutyl vinyl ether macromonomer, unsaturated carboxylic acid, unsaturated sulfonate and an unsaturated ester micromonomer as a comonomer, and an initiator and a chain transfer agent as a molecular regulator for copolymerization reaction. A mass ratio of the 4-hydroxybutyl vinyl ether macromonomer to unsaturated carboxylic acid to unsaturated sulfonate to the unsaturated ester micromonomer to the initiator to the chain transfer agent to deionized water is (24-120):(4-8):(6-8):(10-20):(0.8-1.5):(0.4-2):(70-120). The invention further provides the preparation method of the water reducer. The water reducer is insensitive to a sand content of a sandstone material in concrete; when the water reducer is used for the concrete with the high sand content, the water reducer has higher water reducing capability and smaller slump loss than the traditional polycarboxylic acid water reducer; and the water reducer solves the problem that the traditional polycarboxylic acid water reducer is sensitive to soil, a raw material of sandstone, in the concrete application.