In order to reveal the structural characteristics of acrylamide-based cross-linked polymer microspheres prepared by water dispersion polymerization method and their influence on the performance of drilling fluid，the acrylamide-based cross-linked polymer microspheres were prepared in an ammonium sulfate aqueous solution medium，using acrylamide（AM），acrylic acid （AA）and methyl propionyloxyethyltrimethylammonium chloride（DMC）as monomers，2，2-azobis（2-methylpropylimidazolium）dihydrochloride as initiator，and N，N'-methylenebisacrylamide complex as crosslinker. The structure of polymer microspheres was characterized by infrared spectroscopy and particle size analysis. The effect of cross-linked polymer microspheres on the performance of drilling fluid was investigated. The results showed that the synthesis conditions of cross-linked polymer microspheres had little effect on the filtration reduction of product，but had a significant effect on the viscosity-enhancing effect of polymer microspheres in drilling fluid. With the increase dosage of AM and crosslinker，the viscosity-enhancing effect of polymer microspheres on drilling fluid was enhanced. There was an additive amount of initiator and a molar ratio of AA to DMC that had the least effect on the viscosity increase of drilling fluid. The acrylamide-based cross-linked polymer microspheres having an average particle diameter of 8.04 μm（particle size range of 2.43—53.72 μm）were prepared by water dispersion polymerization method.The cross-linked polymer microspheres with excellent temperature-resistant performance significantly reduced the filtration of drilling fluid and slightly enhanced viscosity. After being aged at 150℃ ，the filtration reduction of polymer microspheres was influenced a little，but the viscosity-enhancing effect of polymer microspheres to drilling fluid was weakened and their influence on the rheology of drilling fluid was reduced.