High temperature-resistance oil well cement retarder

The invention discloses a high temperature-resistance oil well cement retarder, which is a blend of organic substances and inorganic substances and comprises 1-hydroxy ethylidene-1,1-diphosphonic acid, citric acid, sodium chloride and water in a mass part ratio of 2-4:0.5-1:0.5-1.5:3-5. The sodium chloride, the citric acid and the water are mixed in a stirrer or a synthesis kettle in a weight part ratio and are stirred for 5 to 8 minutes till the sodium chloride and the citric acid completely dissolve in the water; then the 1-hydroxy ethylidene-1,1-diphosphonic acid is added in a mass part ratio; the resulting mixture is stirred for 15 to 20 minutes to prepare the high temperature-resistance oil well cement retarder which is the colorless or yellowish liquid; and molecular complexation is performed by using hydrogen bonds formed between molecules in the cement slurry system to improve the high-temperature resistance of the oil well cement retarder.