This study presents an all-optical ultrafast polarization switching mechanism using nonlinear plasmonic metasurfaces. The research demonstrates a method for achieving fast and efficient polarization switching by utilizing second-harmonic generation (SHG) in a plasmonic metasurface with threefold rotational symmetry. The metasurface, composed of gold nanostructures, enables ultrafast switching with a time of 521 fs and a modulation depth of 97%. The device operates in the near-infrared regime and uses the geometric phase of the pump light to control the polarization of the SH wave. The metasurface allows for dual-channel all-optical switching, enabling parallel information processing. The results show that the proposed metasurface platform is a promising solution for developing high-performance all-optical switches, with potential applications in optical information processing and ultrafast optical switching. The study also highlights the importance of nonlinear optical processes in achieving high-speed and high-modulation-depth optical switches, and demonstrates the potential of plasmonic metasurfaces in this area. The research provides a new approach for all-optical switching, with the ability to control the polarization and amplitude of light in the time domain. The findings suggest that nonlinear plasmonic metasurfaces could be a key component in future optical communication and computing systems.This study presents an all-optical ultrafast polarization switching mechanism using nonlinear plasmonic metasurfaces. The research demonstrates a method for achieving fast and efficient polarization switching by utilizing second-harmonic generation (SHG) in a plasmonic metasurface with threefold rotational symmetry. The metasurface, composed of gold nanostructures, enables ultrafast switching with a time of 521 fs and a modulation depth of 97%. The device operates in the near-infrared regime and uses the geometric phase of the pump light to control the polarization of the SH wave. The metasurface allows for dual-channel all-optical switching, enabling parallel information processing. The results show that the proposed metasurface platform is a promising solution for developing high-performance all-optical switches, with potential applications in optical information processing and ultrafast optical switching. The study also highlights the importance of nonlinear optical processes in achieving high-speed and high-modulation-depth optical switches, and demonstrates the potential of plasmonic metasurfaces in this area. The research provides a new approach for all-optical switching, with the ability to control the polarization and amplitude of light in the time domain. The findings suggest that nonlinear plasmonic metasurfaces could be a key component in future optical communication and computing systems.