A novel metallic waveguide Bragg grating all- optical switch based on surface plasmon polaritons (SPP) is proposed using the enhancement and constraint to light by metal- dielectric- metal waveguide Bragg grating. The material and structure size of this switch are decided according to their modulation affection to the effective refractive index. By adding a metal waveguide filter structure in the switch, the pump and signal light are separated, preventing the disturbance of the pump light to signal light and subsequent light path. The simulation of finite-difference time-domain method results show that the extinction ratio reaches 7.2 dB when the intensity of the pump is 50 MW/cm2, response time is less than 2 ps, and the transverse dimension of this structure is about 400 nm.