A new synthesized polymeric inhibitor (SPI) based on the poly-alkyl phenol formaldehyde and polyamine was introduced as asphaltene deposition inhibitor. A Turbiscan apparatus was used to investigate the stability of precipitated asphaltene in crude oil solutions by adding different concentrations of the SPI. The results of turbidity showed that the SPI could delay the asphaltene deposition and provide high stability of precipitated asphaltene in oil solutions. Then two dynamic experiments, including co-injection of crude oil and CO2 into a sandstone core, were conducted with and without the use of 500mg/L SPI at 173 bar and 50 ℃. The permeability ratio and asphaltene content remained relatively unchanged throughout the core flooding with the use of SPI, which indicated increase of the asphaltene stability in the core sample. However, the permeability ratio and outlet asphaltene content in dynamic experiment without the use of SPI decreased by about 70% and 51%, respectively.