Abstract: A novel CO₂-responsive cationic spherical polyelectrolyte brush (SPB) was synthesized by photoemulsion polymerization, which was composed of a solid polystyrene(PS) core and poly (2-(dimethylamino)ethyl methacrylate) (PDMAEMA) shell densely grafted onto the core surface. The most important property of PS-PDMAEMA is the performance of CO₂ response to Pickering emulsion which could employe CO₂/N₂ as a trigger. Dynamic light scattering (DLS), conductivity measurement, digital photography and polarizing microscope were used to characterize the emulsifying performance of PS-PDMAEMA microspheres. The results confirmed that PS-PDMAEMA was a CO₂-responsive cationic spherical polyelectrolyte brush and could regulate the properties of Pickering emulsion with the help of CO₂/N₂. It could broaden the usage of CO₂ as a green stimulation.