The invention provides an amphoteric polycarboxylate-type efficient water reducing agent with viscosity reduction and antibiotic properties, and belongs to the technical field of concrete admixtures.The general formula of the efficient water reducing agent is shown in the description, wherein R is selected from H or CH3; R1 is selected from alkyl of four to ten carbon atoms; X is selected from Cl, Br, I halogen elements; a, b, c, d, e, f, g, h, i, n are all integers, and a, b, c, d, e are selected from 1-30; f is selected from 2-6, and g is selected from 25-80; and h is selected from 2-8, andi is selected from 10-20. The efficient water reducing agent is prepared through polymerization of raw materials including TPEG, unsaturated carboxylic acid, unsaturated phosphate, a cationic monomerand an antibiotic monomer through free radicals under the effects of an initiator and a chain transfer agent. The invention further provides a preparation method of the efficient water reducing agent. The polycarboxylate water reducing agent has the capabilities of reducing the concrete viscosity and improvethe antimildew and anti-rancid properties of a finished compound polycarboxylate water reducing agent product.