The axial and radial instantaneous velocity signals in impinging stream mixer (ISM) were decomposed to multi-scale and studied by R/S analysis method It showed that different fractal structure at different scales can be explained easily by Hurst analysis and there were different trends of Hs with the different positions Besides, there were some non-periodic components in the system, and in the process of particles impinged reciprocally, the vortex with different scale emerges