To address the high-temperature destabilization of conventional polyacrylamide-based viscosity enhancers in drilling fluids, three microcrosslinked polymers (PAANVCL, PAADEAM and PAANIPAM) were synthesized via aqueous free radical polymerization. These polymers incorporated N-vinyl caprolactam (NVCL), N, N-dimethyl acrylamide (DEAM), and N-isopropyl acrylamide (NIPAM) as temperature-sensitive monomers, respectively. The molecular structures were characterized by infrared spectroscopy ( FT-IR), proton nuclear magnetic resonance (¹H-NMR), and X-ray diffraction (XRD), while ultraviolet-visible (UV-vis) spectroscopy was employed to determine the lower critical solution temperature (LCST) and temperature-sensitive behavior. The influence of shear rate and saline conditions on the temperature-sensitive thickening properties of the polymers was investigated, along with their performance in drilling fluids at elevated temperatures. Results indicate that the choice of monomer significantly affects temperature-sensitive performance such that PAANVCL exhibits an LCST of 80 ℃, which surpasses that of PAADEAM (74 ℃) and PAANIPAM (70 ℃). At a shear rate of 18 r/ min, PAANVCL achieves a temperature-sensitive thickening rate of 1.74, compared to 1.60 for PAADEAM and 1.48 for PAANIPAM over the temperature range of 25 ~ 100 ℃. In a 10% NaCl solution at a shear rate of 6 r/ min, PAANVCL maintains a thickening rate of 1.45, while PAADEAM and PAANIPAM record rates of 1.24 and 1.38, respectively. After aging at 160 ℃ for 16 h, PAANVCL-based drilling fluids retain 83% of their viscosity, outperforming PAADEAM (75% ) and PAANIPAM (74.6% ). Thus, the cyclic temperature-sensitive groups of PAANVCL confer exceptional shear, saline and thermal resilience, making it promising for high-temperature and saline drilling fluid applications.