Abstract: To study the velocity field of ESCP (electrostatic centrifugal precipitator), velocity fields of different sections under different inlet velocities were measured with PIV (particle image velocimetry). The test results showed that the radial velocity is minimal and the tangential velocity varies greatly with the axial and radial position in the ESCP. The method has many advantages such as no disturbance in the velocity field, measuring the whole field with thousands of spots simultaneously and so on.