The invention discloses a low-sensitivity anti-mud crossed branched chain type polycarboxylate superplasticizer and a preparation method thereof. The polycarboxylate superplasticizer comprises, by weight, the raw materials of 10-60 parts of 4-hydroxyl vinyl polyoxyethylene ether, 0-40 parts of allyl polyoxyethylene polyether, 0-40 parts of methyl allyl ether polyoxyethylene polyether, 0-40 parts of isopentenyl polyoxyethylene polyether, 6-10 parts of unsaturated monocarboxylic acid, 3-6 parts of unsaturated carboxylic ester monomers, 2-6 parts of 2-(dimethylamino)ethyl methacrylate, 2-6 parts of dibutyl maleate, 1-5 parts of unsaturated amphoteric quaternary phosphonium, 0.2-0.8 part of oxidant, 0.2-1.0 part of first reducing agent, 0.02-0.06 part of second reducing agent, 0.2-0.6 part of chain transfer agent and an appropriate quantity of a potassium hydroxide water solution and a sodium hydroxide water solution and an appropriate amount of deionized water. Lateral chains of the polycarboxylate superplasticizer are distributed more uniformly, are good in slump loss resistance, and the polycarboxylate superplasticizer has excellent low-sensitivity performance for the amount change of the doped polycarboxylate superplasticizer.