Abstract: In order to research into the flow characteristic of power law fluid's helical flow in concentric an-nulus, an experimental model was established. Particle images in various flow fields of annulus helical flow were screened with PIV (Particle Image Velocimetry) technology. The results indicate that when power law fluid is doing helical flow in concentric annulus pipeline, increase of flow rate and fluid's viscosity and decrease of inner pipe's revolution can make the pressure gradient increase; when other conditions are the same, the increase of pressure gradient or flow rate can make the axial velocity increase and promote the happening of turbulent flow; when the pressure gradient is constant, decrease of viscosity or increase of in-ner pipe's revolution can increase the axial velocity, and promote the happening of turbulent flow. Actually measured velocity and theoretical arithmetic velocity in all conditions were compared, the biggest relative error is 4.8%, and the theory tallies with PIV testing experiment results very well.