The invention discloses a synthesis method of quaternary copolymerized salt-resistant and temperature-resistant polyacrylamide. The synthesis method comprises the following steps: firstly, adding acrylamide, a salt-resistant functional monomer, a temperature-resistant functional monomer, a pH buffering monomer and deionized water into a reaction device to prepare a mixed aqueous monomer solution,adjusting the pH value to be 5 to 8, inflating nitrogen to remove oxygen, and adding azodiisobutylimidazoline hydrochloride; after the oxygen content is lower than 0.1mg/L, controlling the temperatureto be at 0-8 DEG C, and reacting for 4-8 hours in a sealed state; then, crushing colloid, mixing with a hydrolyzing agent, preserving heat at 60-80 DEG C, reacting for 4-8 hours, drying and crushingto obtain a finished product. The synthesis method has the advantages as follows: the synthesis method is simple, and the synthesized finished product changes a single molecular structure of the conventional polyacrylamide; the functional monomers are introduced into a main chain to generate special functional groups, so that the sensitivity of the polyacrylamide to salt and the temperature is reduced, therefore, the salt resistance and the temperature resistance of the polyacrylamide are greatly improved, and the quaternary copolymerized salt-resistant and temperature-resistant polyacrylamidecan be better applied to tertiary oil recovery of a high-salt and high-temperature reservoir of an oilfield; moreover, sewage can be used for preparing the quaternary copolymerized salt-resistant andtemperature-resistant polyacrylamide, so that the oil recovery cost is effectively reduced.