Long-term water injection in oilfields leads to high water cut in oil wells，necessitating the development of environmentally friendly，low-cost，high-quality，and efficient chemical agents for profile adjustment and water shutoff. Using polyvinyl alcohol （PVA），rubber powder，glutaraldehyde，and a self-prepared hydrophobic modifier as raw materials，a thermoplastic flexible particle profile adjustment and water shutoff agent that could be formed in one step in aqueous phase was prepared. The particle size and microstructure of the profile modification and water shut-off agent were analyzed，and then its mechanical properties were evaluated using texture analysis method. The stability of the agent was examined under the conditions of high-salinity water and temperatures ranging from 120 ℃ to 200 ℃. A full-penetration fracture model was used to investigate the injection，transport and blockage effects of the agent in fractures. The results showed that when the mass ratio of rubber powder and PVA was between 0 and 1.75，flexible particles with an advantageous particle size of 10—20 mesh（2.00—0.85 mm）could be prepared，significantly reducing synthesis costs. Compared to particles without rubber powder，the rubber powder-doped flexible particles exhibited a loose and porous structure，higher thermal stability，and better mechanical properties. The weight loss temperature increased from 200 ℃ to 300 ℃，the hardness increased from 18.73 N to 37.31 N，the elasticity increased from 0.86 to 0.99，the resilience increased from 0.48 to 0.60，and then the chewiness increased from 15.39 N to 35.88 N. The flexible particles remained stable in high-temperature and high-salinity water，without impact on mechanical properties after aging 60 days at 120 ℃. The particles exhibited good thermoplasticity，beginning to adhere together after aging 3 days. Physical model experiments demonstrated that rubber powder-doped flexible particles could form stable pressure fluctuations，quickly adapt to fracture deformation and pressure changes，and effectively block fractures，with a blockage efficiency of 85.7%. The rubber powder-doped flexible particles possessed excellent deformability，thermal stability and injectivity，which were suitable for improving deep liquid flow redirection in high water cut oilfields and enhancing oil recovery.