Abstract: In view of the problem that existing polymer tackifiers have the defect of viscosity reduction at high temperature and cannot effectively regulate the high-temperature rheological properties of solid-free water-based drilling fluid, acrylamide (AM)/new thermo-sensitive monomer (MVC)/sodium 2-acrylamido-2-methylpropane sulfonate (NaAMPS)comb-type thermo-sensitive polymer (TSP-Comb)was prepared by free radical micellar polymerization. The molecular structure and weight-average molecular weight of TSP-Comb were characterized and measured by infrared spectroscopy, nuclear magnetic hydrogen spectroscopy and gel permeation chromatography. The thermal stability and microstructure of TSP-Comb molecular chain were measured by thermo gravimetric analysis (TGA)and environmental SEM, respectively. The temperature response characteristics of TSP-Comb was studied using rheometer and visible spectrophotometer, and the regulation effect of TSP-Comb on the high-temperature rheological properties of solid-free water-based drilling fluid was also studied. The results show that TSP-Comb solution has excellent high-temperature thickening property within the temperature range of 90 ℃ to 180 ℃ and higher phase transition temperature (higher than 60 ℃). Compared with linear thermo-sensitive polymers, TSP-Comb has been significantly improved in terms of high-temperature rheological stability and phase transition temperature. The high-temperature thickening property of TSP-Comb helps improve the high-temperature rheological properties of solid-free drilling fluid. The change rate of rheological parameters such as apparent viscosity, plastic viscosity and dynamic shear force of solid-free drilling fluid based on TSP-Comb was lower than 25 % within a wide temperature range of 90 ℃ to 180 ℃, and TSP-Comb has significantly improved the high-temperature rheological stability of solid-free drilling fluid, providing a new method for regulating the high-temperature rheological properties of solid-free water-based drilling fluid.