Two-dimensional Bi₂Se₃ nanosheets with hexagonal shape are synthesized by a solution synthetic route. The Bi₂Se₃ nanosheets are 120 nm in edge width and 7 nm in thickness. The size of the Bi₂Se₃ nanosheets can be controlled by choosing different kinds of reducing agents including hydroxylamine and ethylenediamine. Subsequently, we demonstrate a configuration of two-color all-optical switching based on plasma channels effect using the as-synthesized Bi₂Se₃ nanosheets as an optical media. The signal light can be modulated as two states including dot and ring shape by changing the intensity of control light. The modulated signal light exhibits excellent spatial propagation properties. As a type of interesting optical material, ultrathin two-dimensional Bi₂Se₃ nanosheets might provide an effective option for photoelectric applications.