When artificially synthesized polymers are used as filtrate reducers for water-based drilling fluids，it is difficult to meet the needs of drilling engineering by simply changing the type and proportion of copolymer functional groups. Increasing the usage of energetic monomers will undoubtedly increase the cost，especially under ultra-high temperature and high salinity conditions. This study prepared a filtrate reducer with dual cross-linking structure by adding salt resistant monomer 2-acrylamide-2-methylpropanesulfonic acid （AMPS） and temperature resistant monomer N-vinylpyrrolidone （NVP） to the main monomer acrylamide（AM），simultaneously using a very small amount of organic cross-linking agent N，N'-methylenebisacrylamide（MBA） and metal cross-linking agent zirconium citrate（MC）. Using the high-temperature filtration reduction effect of polymers as the evaluation index，single factor experiments were used to optimize the synthesis conditions. The particle size distribution， microstructure，surface morphology，heat resistance，and temperature resistance mechanism of copolymers were analyzed using laser particle size analyzer，Fourier transform infrared spectroscopy，scanning electron microscope，and thermogravimetric analyzer. The results showed that the optimum preparation conditions for the filtrate reducer were obtained as follows：18∶1∶1 the mass ratio of AM，AMPS and NVP monomers，1∶3 the mass ratio of MBA and MC，1.0% initiator dosage，400 r/min stirring speed，and 65 ℃ reaction temperature. The average particle size of filtrate reducer with dual cross-linking structure was 16.48 μm. Its temperature resistance could reach to 350 ℃. The high temperature and high pressure filtration loss and API filtration loss of the system containing 5000 mg/L polymer decreased from 77.6 mL and 18.8 mL to 31.4 mL and 6.8 mL respectively after 16 hours of hot rolling at 210 ℃. The high-temperature resistance mechanism of the filtrate reducer with dual cross-linking structure was that the hydrolyzed polymer molecular chains underwent secondary crosslinking with metal cross-linking agent，protecting the hydrolyzed polymer molecular chains from rapid degradation and forming a more dense and complex three-dimensional network structure，resulting in excellent temperature and salt resistance filtration reduction performance.