The invention relates to an oil well cement retarder in the field of oil gas well exploration and development and a preparation method of the oil well cement retarder. The amphoteric polymer retarder is prepared from, by mass, 10-20% of dimethyldiallylammonium chloride (DMDAAC), 20-30% of 2-acrylamide-2-methyl propane sulfonic acid (AMPS), 30-50% maleic anhydride (MA) and 10-30% of acrylic amide (AM). Due to lateral groups in an amphoteric polymer structure, a self-response type response can be made for the temperature of surroundings, and the temperature adaptability is high. The delayed coagulation of cement paste within the whole temperature region with 70 DEG C and 140 DEG C as the upper and lower end temperatures of a cementing well section is achieved, the thickening time of the cement paste and the retarder added amount are in the good linear relation, the right-angled thickening effect is obvious, the temperature and the added amount sensitivity are low, and the cement paste comprehensive performance can meet the requirement for well cementation construction; in addition, the retarder is simple in synthesis technology, low in cost, high in operability and capable of achieving large-scale production and application.